identification and functional importance of tyrosine sulfate residues within recombinant factor viii.sulfated tyrosine residues within recombinant human factor viii were identified by [35s]sulfate biosynthetic labeling of chinese hamster ovary cells which express human recombinant factor viii. alkaline hydrolysis of purified [35s]sulfate-labeled factor viii showed that greater than 95% of the [35s]sulfate was incorporated into tyrosine. [3h]tyrosine and [35s]sulfate double labeling was used to quantify the presence of 6 mol of tyrosine sulfate per mole of factor viii. amino acid sequence analys ...19921554716
construction of a dominant selectable marker using a novel dihydrofolate reductase.simian virus 40 promoter-enhancer-based mammalian expression plasmids using dihydrofolate reductase (dhfr)-encoding cdna sequences originally isolated from two methotrexate (mtx)-resistant, dhfr-overproducing chinese hamster lung cell lines were constructed. one, designated psva75, contains a dhfr cdna that encodes leucine (leu22) and corresponds to the wild type (wt), mtx-sensitive form of the enzyme [melera et al., j. biol. chem. 263 (1988) 1978-1990]. the other plasmid, psva3, contains a cdna ...19921555767
recovery of sublethal radiation damage and its inhibition by hyperthermia in normal and transformed mouse cells.radiation resistance may be related in part to the capacity of cells to repair radiation damage which can usually be characterized by the survival curve shoulder and split dose recovery. c3h-10t1/2 normal and transformed cells and v79 cells were evaluated for their ability to recover from sublethal radiation damage and for hyperthermia to affect this recovery. the transformed cell line of the 10t1/2 cell system displayed a much larger capacity to recover from radiation damage than did the parent ...19921555949
the human cytokine i-309 is a monocyte chemoattractant.the human cytokine i-309 is a small glycoprotein secreted by activated t lymphocytes and structurally related to a number of inflammatory cytokines. to investigate the biological activities of i-309 protein, we produced a stable chinese hamster ovary cell transfectant, cdi.10, which constitutively secretes i-309 protein into culture supernatant. affinity chromatography on a heparin-sepharose matrix followed by reverse-phase hplc was used to purify to homogeneity a glycoprotein doublet of 15-16 k ...19921557400
isolation and initial characterization of a large repeat sequence element specific to mouse chromosome 8.a clone containing 15.6 kb of mouse genomic dna was specifically localized to murine chromosome 8 by fluorescence in situ hybridization. the major signal, mapping just below the centromeric heterochromatin, was much too intense for a single-copy probe. two additional weak hybridization signals were detected in or near distal bands 8b3 and 8d. six subclones spanning the entire 15.6-kb insert gave strong centromere proximal signals; however, none of these clones cross-hybridized with each other, s ...19921559702
activation of phospholipase d by protein kinase c. evidence for a phosphorylation-independent mechanism.the role of protein kinase c (pkc) in the regulation of phosphatidylcholine-hydrolyzing phospholipase d (pld) was investigated. in membranes from chinese hamster lung fibroblasts that had been incubated with [14c]choline to label endogenous phosphatidylcholine, phorbol 12-myristate 13-acetate (pma) failed to stimulate production of [14c]choline. however, stimulation was observed if fibroblast cytosolic fraction or pkc partially purified from this fraction was added. when incubated with membranes ...19921559964
brefeldin a binds to glutathione s-transferase and is secreted as glutathione and cysteine conjugates by chinese hamster ovary cells.radioactively labeled brefeldin a was used to probe for proteins that interact with this metabolite. the most prominent protein labeled after in vivo incubation of chinese hamster ovary cells with [3h]brefeldin a turned out to have an apparent molecular mass of 26 kda. radioactive peptides derived from the [3h]brefeldin a-labeled protein showed sequence identity with glutathione s-transferases, and immunoblotting after two-dimensional gel electrophoresis confirmed this result. in addition, chine ...19921560007
the signal anchor and stem regions of the beta-galactoside alpha 2,6-sialyltransferase may each act to localize the enzyme to the golgi apparatus.the beta-galactoside alpha 2,6-sialyltransferase has been localized to the trans cisternae of the golgi apparatus and the trans golgi network where it transfers sialic acid residues to terminal positions on n-linked oligosaccharides. it is a type ii transmembrane protein possessing a 9-amino acid amino-terminal cytoplasmic tail, a 17-amino acid signal anchor domain, and a 35-amino acid stem region which tethers the large luminal catalytic domain to the membrane anchor. previous work has demonstr ...19921560012
localization and dna sequence of a replication origin in the rhodopsin gene locus of chinese hamster cells.a chromosomal origin of dna replication has been localized within the single-copy rhodopsin gene locus in chinese hamster (line cho) cells using two methods. in the first method, single-copy segments were identified at 3 to 15 kb intervals within approximately 75 kb (kb = 10(3) bases) of cloned genomic dna containing the early-replicating rhodopsin gene near its middle. the cloned single-copy segments were then used as hybridization probes to quantify the replication of their corresponding genom ...19921560457
the effect of 45 degrees c hyperthermia on the membrane fluidity of cells of several lines.the membrane fluidity of cells of human (ag1522 human foreskin fibroblasts), rodent [chinese hamster ovary (cho) and radiation-induced mouse fibrosarcoma], and feline (crandall feline kidney) cell lines after heating at 45 degrees c was measured by flow cytometry. in addition, a heat-resistant variant of radiation-induced mouse fibrosarcoma cells and two heat-sensitive cho strains were studied. fluorescence polarization of the plasma membrane probe trimethylammonium-diphenylhexatriene was used a ...19921561318
a sequestered pool of aminoacyl-trna in mammalian cells.we have recently proposed that aminoacyl-trna is channeled during protein synthesis in vivo--i.e., it is directly transferred among the components of the protein-synthesizing machinery and does not mix with aminoacyl-trna molecules introduced from outside the cell. to understand the structural basis for these functional properties, we have examined the disposition of aminoacyl-trna within the cell. to do this we have developed a chinese hamster ovary (cho) permeabilized-cell system using the pla ...19921565655
[the combined action of gamma irradiation and hyperthermia on the structure of the cell population in the chinese hamster].a change in the structure of faf-28 chinese hamster cell population occurred during 24 h following gamma-irradiation or hyperthermia heating, or the effect of both factors was studied by flow cytofluorometry. with radiation delivered immediately after heating the distribution of cells among cycle phases was nearly the same as with hyperthermia alone: the share of cells at the s-phase was invariable during the first 4-6 h, then it slowly diminished; at g1 it slowly decreased and at g2 increased. ...19921565762
[biogenesis of peroxisome--targeting signal and peroxisome assembly factor].peroxisome, an ubiquitous subcellular organelle in eukaryotes, functions in many crucial pathways in metabolisms such as catabolism by beta-oxidation of very long chain fatty acids, biosynthesis of etherglycerolipids, and metabolism of cholesterol. to address the question how peroxisomes are assembled in eukaryotic cells, we discuss here two topics undertaken in our laboratory. peroxisomes are formed by posttranslational assembly mechanism; peroxisomal proteins are synthesized on free polysomes ...19921567655
surfactant protein c precursor is palmitoylated and associates with subcellular membranes.surfactant protein c (sp-c) is a 3.7 kda, hydrophobic protein that enhances the adsorption of phospholipids in pulmonary surfactant. sp-c is generated by proteolytic processing of a 21 kda precursor. murine fetal lung explant cultures and a chinese hamster ovary cell line expressing recombinant human sp-c gene (cho/spc) were used to determine the subcellular location and post-translational modification(s) of prosp-c. after in vitro translation, prosp-c of mr = 21,000 was generated. prosp-c was a ...19921567893
sequence requirements for precursor cleavage within the constitutive secretory pathway.we have recently demonstrated that the arg-x-lys/arg-arg sequence is a signal for precursor cleavage catalyzed by furin, a mammalian homologue of the yeast precursor-processing endoprotease kex2, within the constitutive secretory pathway. in this study, we further examined sequence requirements for the constitutive precursor cleavage by expression of various prorenin mutants with amino acid substitutions around the native lys-arg cleavage site in chinese hamster ovary cells. the results delineat ...19921569080
recombinant human thyrotropin stimulates thyroid function and radioactive iodine uptake in the rhesus monkey.the administration of bovine tsh to stimulate thyroid radioactive iodine uptake to detect functioning thyroid tissue in man after surgery for thyroid cancer is rarely, if ever, used, due to allergic reactions and/or the development of tsh antibodies. human (h) tsh would be far less likely to induce allergic reactions or tsh antibodies. recombinant htsh (rec-htsh) was produced by a line of chinese hamster ovary cells that had been transfected with cdna for the two subunit proteins that comprise h ...19921569160
development and characterization of a whole-cell radioligand binding assay for [125i]gp120 of hiv-1.the binding of hiv-1 envelope glycoprotein, gp120, to the cd4 receptor is an important step in productive infection. the development of agents which interrupt this binding phenomenon should be of therapeutic interest. the present study characterizes a whole cell gp120/cd4 radioligand binding assay (radioligand binding assay) modified for use in a high volume screening format. modifications include the use of human cd4 receptor stably expressed in a chinese hamster ovary cell line and the gentle ...19921569213
chinese hamster ovary cells produce an enzyme that nicks heat-labile enterotoxin from enterotoxigenic escherichia coli.chinese hamster ovary (cho) cells were examined for production of an enzyme that nicked the polypeptide chain of the heat-labile enterotoxin from enterotoxigenic escherichia coli between the a1 and a2 fragments of its a subunit. serum-free culture medium prepared each day after cho cell inoculation was concentrated 100 times and its proteolytic activity for formation of the a1 fragment was examined by western blotting with anti-lt a antibody. the a subunit was detected in culture medium on day 6 ...19921572434
cloning and characterization of a rat gene encoding ornithine decarboxylase antizyme.we cloned an ornithine decarboxylase antizyme-encoding gene (oaz) from a rat liver genomic library. the entire gene was located on a 4367-bp ecori fragment, which corresponded to one of two fragments hybridizable with the antizyme-encoding cdna, z1, on southern blot analysis. sequence analysis of the cloned gene showed that it consisted of five exons which were identical with the cdna. the transcription start points of the oaz mrna were located 75 and 76 nucleotides upstream from the first atg c ...19921572540
a conserved region in human and chinese hamster x chromosomes can induce cellular senescence of nickel-transformed chinese hamster cell lines.cellular senescence is the genetically programmed cessation of cellular proliferation. we have recently mapped a putative senescence gene(s) on the x chromosome of chinese hamster embryo (che) cells. in the present study, we have utilized microcell-mediated chromosome transfer (microcell fusion) to test whether: (i) the human x chromosome exhibits similar genetic potential to induce senescence and (ii) the deletion or inactivation of the x-linked senescence gene(s) in che cells is associated wit ...19921576706
reversion of the hprt mutant clone sp5 by intrachromosomal recombination.the spontaneous hprt mutant clone sp5, derived from v79 chinese hamster cells, was shown to exhibit a duplication of approximately 2 kb, including exon 2 and its flanking intron sequences, inserted into the intron 1 sequence of the hprt gene. the most striking feature of sp5 is that this clone is quite unstable, demonstrating an extremely high spontaneous reversion frequency. molecular analysis of 25 independent revertant clones of sp5 indicated that they arose after precise deletion of the dupl ...19921576714
kinetics of folding and assembly of the human chorionic gonadotropin beta subunit in transfected chinese hamster ovary cells.we have employed chinese hamster ovary (cho) cell lines transfected with either the wild type human chorionic gonadotropin beta (hcg-beta) gene alone (cho beta cells) or in conjunction with the gene expressing the alpha subunit (cho alpha,beta cells) to study the folding pathway of the hcg-beta subunit. in both cho beta and cho alpha,beta cells, the earliest detectable hcg-beta precursor, p beta 1, which had two of six potential disulfide bonds (34-88 and 38-57) formed, was converted to p beta 2 ...19921577726
hyaluronate binding properties of versican.we have previously cloned a large chondroitin sulfate proteoglycan (versican) from human fibroblasts. the primary sequence shows that the n terminus contains sequence homology with known hyaluronate-binding molecule, suggesting that versican can bind hyaluronate. to test this hypothesis we have reconstructed a full-length versican cdna and a versican cdna fragment encoding the n terminus and have transfected chinese hamster ovary cells and mouse 3t3 fibroblasts, respectively, with these construc ...19921577773
retention of secretory proteins in an intermediate compartment and disappearance of the golgi complex in an end4 mutant of chinese hamster ovary cells.mutant v.24.1, a member of the end4 complementation group of temperature-sensitive cho cells, is defective in secretion at the restrictive temperature (wang, r.-h., p. a. colbaugh, c.-y. kao, e. a. rutledge, and r. k. draper. 1990. j. biol. chem. 265:20179-20187; presley, j. f., r. k. draper, and d. t. brown. 1991. j. virol. 65:1332-1339). we have further investigated the secretory lesion and report three main findings. first, the block in secretion is not due to aberrant folding or oligomerizat ...19921577851
cloning and expression of the canine interferon-gamma gene.the canine interferon-gamma (cifn-gamma) chromosomal gene was isolated from a recombinant library, containing the entire dog genome, by screening with a rat ifn-gamma genomic probe. the structural organization of the cifn-gamma gene closely resembles that of the human, murine, and rat ifn-gamma genes. it contains three intervening sequences and encodes a signal sequence of 23 amino acids followed by a mature protein of 143 amino acids. two potential n-glycosylation sites are located at positions ...19921578190
characterization of the galactose-specific binding activity of a purified soluble entamoeba histolytica adherence lectin.we studied galactose (gal)-specific binding of the soluble purified 260-kda entamoeba histolytica adherence protein to glycosylation deficient chinese hamster ovary (cho) cell mutants. our goal was to further define the lectin's functional activity and carbohydrate receptor specificity. the adherence protein was purified by acid elution from an immunoaffinity column; however, exposure of the surface membrane lectin on viable trophozoites to identical acid ph conditions had no effect on carbohydr ...19921578406
the analysis of 10 potential spindle poisons for their ability to induce crest-positive micronuclei in human diploid fibroblasts.ten compounds selected for use within a coordinated commission of the european communities programme on aneuploidy induction (cadmium chloride, chloral hydrate, colchicine, diazepam, econazole, hydroquinone, pyrimethamine, thiabendazole, thimerosal and vinblastine) were tested for their ability to induce crest-positive micronuclei in cultured human diploid fibroblasts. significant increases in crest-positive micronuclei were produced by cadmium chloride, chloral hydrate, colchicine, diazepam and ...19921579065
chromosomal aberration tests in vitro: problems with protocol design and interpretation of vitro chromosomal aberration (ca) tests have come to play a central role in testing for mutagenic/carcinogenic potential of chemicals in most countries. guidelines on the conduct of such assays have therefore been published by a variety of sources, and, if anything, recommended protocols have become even more extensive as time has progressed and revisions have been made. yet there is very little comparative data from within or between laboratories to form a basis for these recommendations. so ...19921579073
isolation and partial characterisation of a chinese hamster o6-alkylguanine-dna alkyltransferase cdna.the cdna encoding chinese hamster o6-alkylguanine-dna-alkyltransferase (atase) has been isolated from a library prepared from rna isolated from v79 lung fibroblasts which had an upregulated level of this repair activity following stepwise selection with a chloroethylating agent (1, 2). expression of the cdna in e. coli produced functionally active atase at levels of 2.5% of total cellular protein as determined by in vitro assay. the recombinant hamster protein has a molecular weight of 28 kda as ...19921579490
heterogeneity of microtubule organizing center components as revealed by monoclonal antibodies to mammalian centrosomes and to nucleus-associated bodies from dictyostelium.the molecular composition of two morphologically distinct microtubule-organizing centers (mtocs) was compared by probing with monoclonal antibodies raised against (i) nucleus-associated bodies (nabs) isolated in a complex with nuclei from the cellular slime mold dictyostelium discoideum and (ii) mammalian mitotic spindles isolated from chinese hamster ovary (cho) cells. the staining patterns observed by immunofluorescence microscopy in whole cho cells and dictyostelium amoebae showed that the di ...19921581981
conversion of human interferon-beta from a secreted to a phosphatidylinositol anchored protein by fusion of a 17 amino acid sequence to its carboxyl terminus.a number of cell-surface proteins are anchored in plasma membranes by a glycosylated phosphatidylinositol (pi) moiety that is covalently attached to the carboxyl-terminal amino acid of the mature protein. we have previously reported the construction of a cdna clone of a truncated platelet-derived growth factor (pdgf) receptor that consists of the extracellular domain without the transmembrane and cytoplasmic domains. in the construction of the vector, a sequence of 51 base pairs (bp) from the 3' ...19921584209
studies on the role of amino acids 38-45 in the expression of a functional thyrotropin receptor.we previously reported that deletion or substitution of a unique eight-amino acid tract (residues 38-45) in the extracellular domain of the human tsh receptor led to the loss of specific ligand binding to the surface of transfected cells. in the present study we analyzed this region in more detail. using site-directed mutagenesis of the tsh receptor cdna, we substituted amino acid residues 38-45, either in three overlapping groups of four amino acids each or individually. the resultant tsh recep ...19921584215
confirmation of assignment of the bovine k-casein locus by pcr.the provision of a bovine gene map will allow the ready identification of genetic disease in cattle and will lead to the identification of the genetic loci responsible for quantitative traits of economic importance. an extension of the polymerase chain reaction to the identification of linkage in bovine-chinese hamster cell hybrids has improved the speed and facility of the assignment of genes to linkage groups and thus makes it easier to achieve a bovine linkage map.19921585084
isopentenoid synthesis in embryonic drosophila cells: prenylated protein profile and prenyl group has been established that vertebrates and yeasts modified a unique subset of polypeptides with farnesyl and geranylgeranyl residues. this observation has been extended to drosophila kc cells. [3h]mevalonate was incorporated into 54 kc cell peptides (18-92 kda). as reported for mammalian cells, most of the labeled peptides had molecular weights between 21 and 27 kda. c18 radio-hplc tryptic digest profiles for delipidized, [3h]mevalonate-labeled (a) insect (drosophila and spodoptera frugiperda) ...19921586169
cloning of a member of the arrestin family from a human thyroid cdna library.we used the cdna of human retinal arrestin as a probe to screen a human thyroid cdna library. we isolated and plaque-purified one clone (hthy-arrx). the nucleotide sequence of the 1.8 kb cdna insert had an open reading frame of 1227 bp coding for a protein of 409 amino acids. northern blot analysis revealed a single transcript of 1.7 kb in human thyroid cells. there is significant homology between amino acid sequences of human thyroid arrestin and human retinal arrestin (63%) and bovine beta-arr ...19921587386
molecular and enzymatic properties of furin, a kex2-like endoprotease involved in precursor cleavage at arg-x-lys/arg-arg sites.we have recently shown that furin, a mammalian homologue of the yeast precursor-processing endoprotease kex2, is involved in precursor cleavage at sites marked by the arg-x-lys/arg-arg motif within the constitutive secretory pathway. in this study, we analyzed molecular and enzymatic properties of furin expressed in chinese hamster ovary cells using gene transfer techniques. cooh-terminal truncation analyses indicate that the polypeptide region significantly conserved among the kex2 family membe ...19921587790
n-linked glycosylation of rabies virus glycoprotein. individual sequons differ in their glycosylation efficiencies and influence on cell surface expression.many eukaryotic proteins are modified by n-linked glycosylation, a process in which oligosaccharides are added to asparagine residues in the sequon asn-x-ser/thr. however, not all such sequons are glycosylated. for example, rabies virus glycoprotein (rgp) contains three sequons, only two of which appear to be glycosylated in virions. to examine further the signals in proteins which regulate n-linked core glycosylation, the glycosylation efficiencies of each of the three sequons in the antigenic ...19921587845
cloning, expression, and characterization of the unique bovine a1 adenosine receptor. studies on the ligand binding site by site-directed mutagenesis.the bovine brain a1 adenosine receptor (a1ar) is distinct from other a1ars in that it displays the unique agonist potency series of n6-r-phenylisopropyladenosine (r-pia) greater than n6-s-phenylisopropyladenosine (s-pia) greater than 5'-n-ethylcarboxamidoadenosine and has a 5-10-fold higher affinity for both agonists and antagonists. the cdna for this receptor has been cloned from a size-selected (2-4-kb) bovine brain library and sequenced. the 2.0-kb cdna encodes a protein of 326 amino acid res ...19921587851
novel responses of human skin to intradermal recombinant granulocyte/macrophage-colony-stimulating factor: langerhans cell recruitment, keratinocyte growth, and enhanced wound healing.recombinant granulocyte/macrophage-colony-stimulating factor (rgm-csf), prepared from chinese hamster ovary (cho) cells and escherichia coli, was administered to 35 patients with the borderline and polar lepromatous forms of leprosy by the intradermal and subcutaneous routes at doses of 7.5-45.0 micrograms/d for 10 d. with each of these doses and routes, increases in the number of circulating eosinophils were noted. after the intradermal injection, the local skin sites demonstrated zones of roug ...19921588289
human tryptase as a potent, cell-specific mitogen: role of signaling pathways in synergistic responses.mast cells are hypothesized to participate in processes leading to tissue fibrosis in human lung and skin. to explore the possible involvement of mast cell mediators in fibrogenesis, the mitogenic activity of mast cell tryptase from human lung was examined in vitro. the results indicate that human tryptase is a potent inducer of dna synthesis in fibroblasts from multiple sources, including human lung. as demonstrated by mitogenic responses in fibroblasts, but not in vascular smooth muscle cells, ...19921590404
the c-terminal domain of the pulmonary surfactant protein c precursor contains signals for intracellular targeting.we have studied the intracellular transport of the pulmonary surfactant sp-c precursor in vitro and in vivo. in order to monitor the route of the sp-c precursor, we constructed various c-terminally truncated forms of sp-c, which were tagged with a sequence derived from the c-terminus of the human c-myc gene (aa 409-419). expression of these constructs under the control of the sv40 enhancer and the humt-ii promoter in stably transformed chinese hamster ovary (cho) cells revealed that the complete ...19921591009
genetic toxicology studies of an anti-aids (n-butyldeoxynojirimycin) is an experimental anti-aids drug which is currently in clinical trials. this drug is an aminosugar derivative. its biological properties have been previously published [1]. since many antiviral agents which are nucleic acid analogs exhibit mutagenic and/or clastogenic properties, the genotoxic potential of sc-48334 was examined in the ames salmonella/microsome assay, the chinese hamster ovary cell/hypoxanthine guanine phosphoribosyl transferase (cho/hgprt) ass ...19921595086
proprotein conversion is determined by a multiplicity of factors including convertase processing, substrate specificity, and intracellular environment. cell type-specific processing of human prorenin by the convertase pc1.proprotein and prohormone processing at pairs of basic residues is generally thought to be both tissue- and precursor-specific and to be developmentally regulated. furin, pc1 (also called pc3), and pc2 represent three recently discovered subtilisin-like proteinases which cleave a number of precursors at the same pairs of basic residues normally processed in vivo. using human prorenin as a model, we show that pc1 can process it to active renin in cells containing secretory granules, such as the s ...19921597471
rat cystathionine beta-synthase. gene organization and alternative splicing.we elucidated the structure and alternative splicing patterns of the rat cystathionine beta-synthase gene. the gene is 20-25 kilobase pairs long, and its coding region is divided into 17 exons. these are alternatively spliced, forming four distinct mrnas (types i through iv). the predicted open reading frames encode proteins of 61.5, 39, 60, and 52.5 kda, respectively. exons 13 and 16 are used alternatively and mutually exclusively. exon 13 includes a stop codon and encodes the unique carboxyl-t ...19921597473
scavenger-receptor-mediated delivery of daunomycin elicits selective toxicity towards neoplastic cells of macrophage lineage.transformed cells of macrophage lineage such as j774a.1, p388d1 and ic21 take up and degrade a conjugate of the antineoplastic drug, daunomycin, with maleylated bsa with high efficiency and saturation kinetics through the scavenger receptors expressed on the surface of these cells. by contrast, transformed cells of non-macrophage lineage, namely l929, el4, bowes melanoma and cho (chinese-hamster ovary), do not take up and degrade the conjugate, indicating that these cells are scavenger-receptor- ...19921599401
expression of drosophila's 27 kda heat shock protein into rodent cells confers thermal resistance.the role of hsp27, one of drosophila melanogaster's small heat shock proteins, in the process of thermotolerance was investigated. the coding sequence of hsp27 was subcloned downstream of the human hsp27 promoter which has been shown to be constitutively expressed in chinese hamster o23 cells. cellular resistance to a thermal stress was measured two days after transfection by a survival assay following a 3.5 h heat treatment at 44 degrees c. expression of drosophila hsp27 was shown to confer the ...19921599446
delayed reproductive death as a dominant phenotype in cell clones surviving x-irradiation.residual damage manifested as reduced cloning efficiency was observed in many of the cloned progeny of chinese hamster ovary (cho) cells and human carcinoma sq-20b cells surviving x-irradiation. this stable phenotype, which we have termed delayed reproductive death, persisted for greater than 50 generations of cell replication post-irradiation. clones showing this phenotype were aneuploid, and formed colonies with a high proportion of giant cells. by somatic cell hybridization of cho clones, the ...19921600612
expression of rat renin in mammalian cells and its purification.rat renin cdna was transfected into cos-7 and chinese hamster ovary (cho) cells and expressed under the control of the simian virus 40 early promoter. conditioned media of the transfected cells showed renin activity only after trypsin treatment, suggesting prorenin was secreted into the medium. from the trypsinized serum-free culture of the transfected cho cells active renin was purified to homogeneity by a simple three-step procedure. the active renin had similar specific activity, molecular we ...19921600638
human chromosome 12 is required for optimal interactions between tat and tar of human immunodeficiency virus type 1 in rodent cells.levels of trans activation of the human immunodeficiency virus type 1 long terminal repeat (hiv-1 ltr) by the virally encoded transactivator tat show marked species-specific differences. for example, levels of transactivation observed in chinese hamster ovary (cho) rodent cells are 10-fold lower than those in human cells or in cho cells that contain the human chromosome 12. thus, the human chromosome 12 codes for a protein or proteins that are required for optimal tat activity. here, the functio ...19921602563
development of assays for the detection of photomutagenicity of chemicals during exposure to uv light. ii. results of testing three sunscreen ingredients.three sunscreen ingredients, derivatives of benzylidene camphor, were tested for photomutagenic potential. these were benzenesulfonic acid, 4-[(4,7,7,-trimethyl-3-oxo-bicyclo [2.2.1] hept-2-ylidene) methyl] (mexoryl sl), 4-(2-oxo 3-bornylidenemethyl) phenyl trimethylammonium methyl sulphate (mexoryl so) and 3,3'-(1,4-phenylenedimethylidyne) bis [7,7-dimethyl-2-oxo-bicyclo [2.2.1] heptane-1-methanesulfonic acid] (mexoryl sx). two complementary assay systems were used, one involving the induction ...19921602971
different fates of the oligosaccharide moieties of lipid intermediates.we have previously described that the n-glycosylation process was accompanied by the release of oligosaccharide-phosphates and neutral oligosaccharides. the relationship between oligosaccharide-p-p-dolichol and its metabolic products (glycoproteins, oligosaccharide-phosphates and neutral oligosaccharides) was investigated by analysing the structure of the oligosaccharide moieties and the kinetic behaviour of the various species in pulse and pulse/chase experiments. for these studies, a glycosyla ...19921606357
assignment of the lens intrinsic membrane protein mp19 structural gene to human chromosome 19.we have isolated and characterized a bovine cdna clone encoding the bovine lens intrinsic membrane protein, mp19. this cdna was used as a probe to analyze a panel of southern blots of human-chinese hamster somatic cell hybrid dnas to assign the gene coding for mp19 to its human chromosome. control human and chinese hamster dnas displayed a distinct ecor1 restriction fragment pattern when hybridized with the bovine mp19 cdna. when somatic cell hybrid dnas were restricted with eco r1 and southern ...19921606837
encapsulation of insulin for oral administration preserves interaction of the hormone with its receptor in has been shown that insulin associated with nanocapsules of isobutylcyanoacrylate retains biological activity after oral administration to diabetic rats from 6 to 21 days. because part of this action is unexplained, we focused on the interaction of encapsulated insulin with the insulin receptor in vitro. we have shown that encapsulated insulin is able 1) to bind to insulin receptors both in rat liver plasma membranes and after solubilization from chinese hamster ovary (cho) cells transfected ...19921607072
sustained reflow in dogs with coronary thrombosis with k2p, a novel mutant of tissue-plasminogen activator.coronary artery reocclusion after thrombolysis with human recombinant tissue-type plasminogen activator (rt-pa) is related to the short half-life of this agent in plasma. k2p, a mutant of rt-pa lacking the fibronectin fingerlike, epidermal growth factor-like and first kringle domains (amino acids 6 to 173) and having the glycosylation site asn184 mutagenized to gln, has been produced in chinese hamster ovary cells. in this study we compared the thrombolytic effect of k2p and rt-pa in dogs with e ...19921607530
related subunits of nf-kappa b map to two distinct loci associated with translocations in leukemia, nfkb1 and nfkb2.the chromosomal locations of the human genes nfkb1 and nfkb2, which encode two alternative dna binding subunits of the nf-kappa b complex, p105 and p49/p100, respectively, have been determined. p105 was assigned to 4q21.1-q24 and p49/p100 to chromosome 10 by southern blot analysis of panels of human/chinese hamster cell hybrids. the locations were confirmed by fluorescence in situ hybridization and mapped with greater resolution to 4q23 and 10q24, respectively. these results demonstrate that the ...19921612589
processing and characterization of recombinant von willebrand factor expressed in different cell types using a vaccinia virus vector.the cloning of the cdna encoding von willebrand factor (vwf) has revealed that it is synthesized as a large precursor (pre-pro-vwf) molecule and it is now clear that the prosequence or vwagii is responsible for the intracellular multimerization of vwf. we have cloned the complete vwf cdna and expressed it using a recombinant vaccinia virus as vector. we have characterized the structure and function of the recombinant vwf (rvwf) secreted from five different cell types: baby hamster kidney (bhk), ...19921615470
restriction of serum antibody reactivity to the v3 neutralizing domain of hiv gp120 with progression to identify epitopes on hiv-1 gp120 that correlate with disease resistance and/or prognostic indication.19921616648
trypsin treatment may impair the interfacial activation action of lipoprotein lipase.lipoprotein lipase was expressed in chinese hamster ovary (cho) cells transfected with human lipoprotein lipase cdna. the lipoprotein lipase retained tributyrin, water-soluble substrate, hydrolyzing activity (esterase activity). the catalytic action of this enzyme was studied by monitoring the esterase activity. the esterase activity was enhanced 4.5-fold by the addition of triolein emulsified with triton x-100. this process was named interfacial activation. treatment of lpl with trypsin (100 mi ...19921618742
overexpression of c-myc by amplification of negative promoter domain.amplification of myc proto-oncogenes has been reported in many human malignancies, but whether the amplified genes are properly regulated has not been well studied. transcription factors that control gene expression are of limited abundance, and we have previously shown (johnston, r.n., and kucey, b.l. (1988) science 242, 1551-1554) that amplified heat shock promoter sequences can compete with natural heat shock genes for these factors, resulting in heat shock gene disregulation. to establish wh ...19921618750
post-transcriptional regulation of 3-hydroxy-3-methylglutaryl coenzyme a reductase by 24(s),25-oxidolanosterol.we have examined the mechanism of regulation of 3-hydroxy-3-methylglutaryl coenzyme a reductase by 24(s),25-oxidolanosterol, a c30-sterol naturally occurring in mammalian tissues. in the absence of enzymatic demethylation to the c27-sterol, 24(s),25-epoxycholesterol, oxidolanosterol is shown to be a post-transcriptional regulator of reductase synthesis in both primary rat hepatocytes and chinese hamster ovary cells. under these conditions, oxidolanosterol also increases the rate of degradation o ...19921618770
enhanced insulin-induced mitogenesis and mitogen-activated protein kinase activities in mutant insulin receptors with substitution of two cooh-terminal tyrosine autophosphorylation sites by phenylalanine.we have studied the function of a mutant human insulin receptor in which two cooh-terminal autophosphorylation sites (tyr-1316 and -1322) were replaced by phenylalanine (f/y cooh-terminal 2 tyrosines (ct2)). in addition, we have also constructed a mutant receptor in which lys-1018 in the atp-binding site was changed to arginine (r/k 1018). both the wild type insulin receptor (hir) and the mutant receptors were expressed in chinese hamster ovary (cho) cells by stable transfection. autophosphoryla ...19921618780
internalization of the human insulin receptor. the insulin-independent pathway.internalization of the human insulin receptor requires the activation by insulin of the intrinsic kinase of the receptor. however, even in the absence of kinase activation, insulin receptors slowly enter the cells. in the present study, we addressed the question of this insulin-independent pathway of internalization. to that end, we traced insulin receptor internalization with a monoclonal antibody (mab 83-14) directed against the alpha-subunit of the human insulin receptor. internalization of t ...19921618809
differential role of insulin receptor autophosphorylation sites 1162 and 1163 in the long-term insulin stimulation of glucose transport, glycogenesis, and protein synthesis.the long-term regulatory effect of insulin on glucose transport activity and glucose transporter expression was examined in chinese hamster ovary (cho) transfectants that overexpress either human insulin receptors of the wild type (cho-r cells) or human insulin receptors mutated at two major autophosphorylation sites, tyr1162 and tyr1163 (cho-y2 cells). previous studies showed that, when acutely stimulated by insulin, cho-y2 cells exhibit decreased receptor kinase activity along with decreased s ...19921618850
interaction of pertussis toxin with cells and model membranes.the interaction of pertussis toxin (pt) with cells and model membranes was investigated by examining pt-induced intoxication of chinese hamster ovary cells and by studying the binding of pt and its subunits to phospholipid vesicles. since certain bacterial toxins require an acidic environment for efficient interaction with membranes and subsequent entry into the cell, the requirement for an acidic environment for pt action was examined. pt, unlike bacterial toxins such as diphtheria toxin, did n ...19921618869
targeted integration of neomycin into yeast artificial chromosomes (yacs) for transfection into mammalian cells.vectors have been constructed for the introduction of the neomycin resistance gene (neo) into the left arm, right arm or human insert dna of yeast artificial chromosomes (yacs) by homologous recombination. these vectors contain a yeast selectable marker lys-2, i.e. the alpha-aminoadipidate reductase gene, and a mammalian selection marker, neo, which confers g418 resistance. the vectors can be used to modify yacs in the most commonly used yeast strain for yac library construction, ab1380. specifi ...19921620591
monitoring gene expression in chinese hamster ovary cells using secreted apoaequorin.a luminescence method for monitoring gene expression in chinese hamster ovary cells using apoaequorin as a secreted reporter enzyme is described. in this method, the cell is not disrupted prior to assay as in the earlier aequorin procedure and in the firefly method. the apoaequorin secretion vector is constructed by fusing the dna fragment of the signal peptide sequence of human follistatin to the apoaequorin gene. transfection of chinese hamster ovary cells with the vector causes the apoaequori ...19921621948
mutagenicity of the new quinolone antibacterial agent levofloxacin.a new quinolone antibacterial agent (-)-(s)-9-fluoro-2,3-dihydro-3-methyl-10- (4-methyl-1-piperazinyl)-7-oxo-7h-pyrido[1,2,3-de][1,4]benzoxazine-6- carboxylic acid hemihydrate (levofloxacin, dr-3355, cas 100986-85-4), was studied for mutagenicity using the following short-term in vitro and in vivo tests. 1. in vitro studies: reverse mutation test (ames method) on s. typhimurium and e. coli; and hgprt forward mutation test, cytogenetic test, and sister chromatid exchange (sce) test, all on chines ...19921622436
chromosome segregation from cell hybrids. vii. reverse segregation from karyoplast hybrids suggests control by cytoplasmic factors.using human and chinese hamster established lines as cell parents, we constructed hamster-human cell hybrids and human cell - hamster karyoplast hybrids. the cell hybrids retained one or two sets of hamster chromosomes and lost most of the human chromosomes. the karyoplast hybrids, however, retained a full set of human chromosomes and lost most of the chinese hamster chromosomes. this reverse segregation pattern implies that cytoplasmic factors are major determinants of the direction of chromoso ...19921624135
models of insulin action on metabolic and growth response ongoing studies aimed at elucidating the mechanism of insulin action on the expression of genes that modulate glucose utilization and cell growth, we have focused on the inductive effect of insulin on transcription of glyceraldehyde-3-phosphate dehydrogenase (gapdh) and the early growth response gene, egr-1. insulin acutely stimulates the expression of both genes in 3t3 adipocytes; however, in primary adipocytes, chronic insulin exposure has opposing effects on the expression of these genes. ...19921625685
effect of fluoride on inhibition of plasma membrane functions in chinese hamster ovary cells photosensitized by aluminum phthalocyanine.fluoride inhibits photohemolysis induced by chloroaluminum phthalocyanine tetrasulfonate (alpcs4) when it is added to dye-loaded human erythrocytes prior to light exposure (e. ben-hur, a. freud, a. canfi, and a. livne, int. j. radiat. biol. 59, 797-806, 1991). this is due to formation of a complex of f- with al3+, leading to selective release and/or modified dye binding with some proteins so that the effective photochemical reaction is prevented. in this work we used f- as a probe to evaluate th ...19921626048
double-minute chromosomes as megabase cloning vehicles.radiation-reduced chromosomes provide valuable reagents for cloning and mapping genes, but they require multiple rounds of x-ray deletion mutagenesis to excise unwanted chromosomal dna while maintaining physical attachment of the desired dna to functional host centromere and telomere sequences. this requirement for chromosomal rearrangements can result in undesirable x-ray induced chromosome chimeras where multiple non-contiguous chromosomal fragments are fused. we have developed a cloning syste ...19921627362
expression and purification of human angiotensinogen in chinese hamster ovary cells.we have produced human angiotensinogen in chinese hamster ovary (cho) cells. the expression products were purified to homogeneity by a single column chromatography and its 17 amino-terminal sequences were identical to those of the native protein. we demonstrated the recombinant human angiotensinogen to be a substrate for human renin.19921627612
replication of distinct scrapie prion isolates is region specific in brains of transgenic mice and hamsters.scrapie prions are composed largely, if not entirely, of prpsc molecules. the prion isolates sc237 and 139h exhibit markedly different incubation times in syrian, armenian, and chinese hamsters, as well as in transgenic (tg) 81 mice expressing syrian hamster prp (shaprp). repassage of prions from transgenic mice or chinese hamsters into syrian hamsters revealed that the original properties of the prion isolates are retained. when syrian hamsters were first inoculated with 139h prions and subsequ ...19921628828
biochemical, thrombolytic and pharmacokinetic properties of rt-pa p47g, k49n, a substitution variant of human tissue-type plasminogen activator.rt-pa p47g, k49n, a substitution variant of recombinant human tissue-type plasminogen activator (rt-pa), in which proline at position 47 and lysine at position 49 were replaced by glycine and asparagine respectively, was previously described by ahern et al. (j biol chem 1990; 265:5540-5) to have an extended in vivo half-life with unaltered in vitro fibrinolytic properties. because this variant might possess an increased in vivo thrombolytic potency, we have constructed its cdna, expressed it in ...19921631793
k1k2pu, a recombinant t-pa/u-pa chimera with increased thrombolytic potency, consisting of amino acids 1 to 3 and 87 to 274 of human tissue-type plasminogen activator (t-pa) and amino acids 138 to 411 of human single chain urokinase-type plasminogen activator (scu-pa). purification in centigram quantities and conditioning for use in man.k1k2pu, a recombinant t-pa/u-pa chimera with increased thrombolytic potency in animal models of venous and arterial thrombosis, which consists of amino acids 1 to 3 and 87 to 274 of human tissue-type plasminogen activator (t-pa) and amino acids 138 to 411 of human single chain urokinase-type plasminogen activator (scu-pa), was produced and conditioned for use in patients. chinese hamster ovary cells were transfected with an expression plasmid containing the k1k2pu cdna, high producer cell lines ...19921631805
the genetic toxicology of cobalt.genetic and related effects of cobalt compounds are reviewed and discussed with respect to mechanisms. in prokaryotic assays, co(ii) salts generally are nonmutagenic. in saccharomyces cerevisiae, cocl2 is mutagenic to mitochondrial genes and weakly mutagenic or nonmutagenic to chromosomal genes. in plants, co(ii) salts induced gene mutations and chromosomal aberrations. in mammalian cells in vitro, co(ii) compounds caused dna strand breaks, sister-chromatid exchanges and aneuploidy, but not chro ...19921631889
feedback repression of polyamine uptake into mammalian cells requires active protein synthesis.two mammalian cell lines, rat hepatoma (htc) and chinese hamster ovary (cho), were fed 10 to 50 microm spermidine while changes were monitored in intracellular polyamine levels and spermidine uptake activity. normal feedback control preventing excessive polyamine uptake was found to be completely blocked by the addition of inhibitors of protein synthesis at the time of polyamine exposure. under these conditions the cells accumulated abnormally high, toxic concentrations of spermidine. further, c ...19921632796
dolastatin 15, a potent antimitotic depsipeptide derived from dolabella auricularia. interaction with tubulin and effects of cellular microtubules.dolastatin 15, a seven-subunit depsipeptide derived from dolabella auricularia, is a potent antimitotic agent structurally related to the antitubulin agent dolastatin 10, a five-subunit peptide obtained from the same organism. we have compared dolastatin 15 with dolastatin 10 for its effects on cells grown in culture and on biochemical properties of tubulin. the ic50 values for cell growth were obtained for dolastatin 15 with l1210 murine leukemia cells, human burkitt lymphoma cells, and chinese ...19921632820
sodium butyrate selectively induces transcription of promoters adjacent to the momsv viral enhancer.the long terminal repeat region of the moloney murine sarcoma virus (momsv) was cloned upstream from the chinese hamster ovary adenine phosphoribosyltransferase (aprt)-encoding gene (aprt) in order to enhance synthesis of the aprt protein. the replacement of the native promoter with the viral enhancer-promoter increased the enzymatic activity of aprt two- to threefold. addition of sodium butyrate (nabu) to the cell growth medium induced aprt activity ten- to 20-fold above wild-type levels in bot ...19921634113
relation between the insulin receptor number in cells, autophosphorylation and insulin-stimulated ras.gtp formation.we showed previously that upon insulin stimulation of an insulin receptor overexpressing cell line, most of the p21ras was rapidly converted into the gtp bound state (burgering, b. m. t., medema, r. h., maassen, j. a., van de wetering, m. l., van der eb, a. j., mccormick, f., and bos, j. l. (1991) embo j. 10, 1103-1109). to determine whether this process also occurs in cells expressing physiologically relevant numbers of insulin receptors, insulin stimulated ras.gtp formation was quantitated in ...19921634512
expression of human ornithine aminotransferase (oat) in oat-deficient chinese hamster ovary cells and fibroblasts of gyrate atrophy patient.gyrate atrophy is a hereditary chorioretinal degenerative disease caused by a deficiency of the mitochondrial enzyme, ornithine aminotransferase (oat). recent investigations have demonstrated the molecular genetic defects of oat in gyrate atrophy patients. we constructed a eukaryotic expression vector (pcdhoat) which contains the sv40 promoter and human oat cdna. we used oat(-) chinese hamster ovary (cho) cells, which have negligible oat activity, and fibroblasts from a gyrate atrophy patient (g ...19921635292
effect of arsenite on the dna repair of uv-irradiated chinese hamster ovary cells.arsenite, an ubiquitous human carcinogen, has been shown to enhance the cytotoxicity, mutagenicity and clastogenicity of uv light in mammalian cells. arsenite may exert its co-genotoxic effects by inhibiting dna repair. results from alkaline sucrose gradient sedimentation show that arsenite did not accumulate uv-induced dna strand breaks in chinese hamster ovary (cho) k1 cells as aphidicolin plus hydroxyurea (hu) did. these data indicate that arsenite did not inhibit the activity of dna polymera ...19921635456
translesion dna synthesis in the dihydrofolate reductase domain of uv-irradiated cho cells.the studies that document the coupling of strand-specific dna repair to transcription of active genes exclude replicated dna from the analysis. yet cyclobutane pyrimidine dimers (cpd) induced by ultraviolet light (uv) persist in most of the genome in surviving chinese hamster ovary (cho) cells. the mechanisms that allow dna replication to occur in the presence of damaged templates are poorly understood. we have investigated the distribution of cpd in the dihydrofolate reductase gene (dhfr) domai ...19921637815
characterization of the oligosaccharide structures on recombinant human prorenin expressed in chinese hamster ovary cells.prorenin was isolated by immunoprecipitation from the culture medium of chinese hamster ovary cells transfected with a human prorenin cdna. the n-linked oligosaccharide structures on the in vivo [3h]mannose-labeled, purified protein were characterized using a combination of serial lectin affinity chromatography, high-pressure liquid chromatography, ion-exchange chromatography, and size-exclusion chromatography and treatment with specific glycosidases and methylation analysis. approximately 61% o ...19921637829
structure-activity study and design of multidrug-resistant reversal compounds by a computer automated structure evaluation methodology.we have studied the relation between the structure and the multidrug resistance-reversal activity of a set of diverse chemicals with the multicase structure-activity program. a number of key structural features were identified as being related to multidrug resistance reversal activity. using these key features, we identified seven new compounds predicted to have substantial activity. these were obtained and tested experimentally on a cho/chrc5 cell line derived from the ab1 chinese hamster ovary ...19921638525
ci-973, a new platinum derivative with potential antileukemic activity.we examined the effects of ci-973 (supplied by parke-davis) on several human leukemia cell lines and a chinese hamster ovary (cho) line and their drug-resistant counterparts. the cell lines used were hl-60, hl-60/mamsa, hl-60/dox, kbm3, kbm3/mamsa 6, kbm3/mamsa 6(85), cho, and cho/ac-7. dox, mamsa, and ac-7 indicate resistance to doxorubicin, amsacrine, or 1-beta-d-arabinofuranosylcytosine, respectively. cells were incubated with ci-973, and the effect was evaluated by two methods: growth inhibi ...19921638526
gene- and strand-specific damage and repair in chinese hamster ovary cells treated with 4-nitroquinoline 1-oxide.4-nitroquinoline 1-oxide (4nqo) is a model chemical carcinogen that has often been referred to as a uv mimetic agent. previous studies have indicated that uv-induced pyrimidine dimers are repaired preferentially and strand-specifically in actively transcribing genes. in the current study we have examined the gene-specific and strand-specific repair of 4nqo in chinese hamster ovary b-11 cells treated with 2.5 microm 4nqo. the methodology used for detecting adducts involved the treatment of dna fr ...19921638532
a recombinant, chimeric enzyme with a novel mechanism of action leading to greater potency and selectivity than tissue-type plasminogen activator.early intervention with thrombolytic agents has been shown unequivocally to reduce mortality after acute myocardial infarction. presently used agents have disadvantages such as short half-life, immunogenicity, hypotension, and bleeding complications. therefore, there is a need to develop improved thrombolytic drugs with novel mechanisms of action leading to improved properties.19921638720
importance of the carboxyl terminus of human thyroid peroxidase in the efficient expression of the protein in eukaryotic cells.carboxyl terminal truncation of membrane-associated human thyroid peroxidase (htpo), with the elimination of its single membrane-spanning and short intracytoplasmic regions, generates a soluble, secreted, enzymatically active protein (amino acids 1-848). in order to determine the effects of further carboxyl terminal deletions on the expression of htpo, chinese hamster ovary cells were stably transfected with plasmids constructed to express amino acids 1-771, 1-636, 1-539 and 1-382 of the 933 ami ...19921639219
[preparation of monosomal lines containing individual human 15, 21, and x chromosomes].sorting of human--mouse or human--hamster hybrid cells with particular human chromosomes was performed by in situ hybridization. total human genomic dna was heavily labelled with. h and hybridized to metaphase spreads from hybrid clone cells. the method allowed us to not only identify human chromosomes in hybrid cells but also to detect terminal translocations and insertions from 1-2 bands in length to large ones. biochemical markers of some human chromosomes were analysed using electrophoretic ...19921639248
synthesis, characterization, and some immunological properties of conjugates composed of the detoxified lipopolysaccharide of vibrio cholerae o1 serotype inaba bound to cholera against cholera has been correlated with the level of serum vibriocidal antibodies. the specificity of these vibriocidal antibodies was mostly to the lipopolysaccharide (lps). we synthesized conjugates of detoxified lps with cholera toxin (ct) and other proteins in order to elicit serum lps antibodies with vibriocidal activity. treatment with hydrazine (deacylated lps) reduced the endotoxic properties of the lps to clinically acceptable levels and resulted in a molecule larger and mor ...19921639490
fusions of anthrax toxin lethal factor to the adp-ribosylation domain of pseudomonas exotoxin a are potent cytotoxins which are translocated to the cytosol of mammalian cells.the lethal factor (lf) and edema factor (ef) components of anthrax toxin are toxic to animal cells only if internalized by interaction with the protective antigen (pa) component. pa binds to a cell surface receptor and is proteolytically cleaved to expose a binding site for lf and ef. to study how lf and ef are internalized and trafficked within cells, lf was fused to the translocation and adp-ribosylation domains (domains ii and iii, respectively) of pseudomonas exotoxin a. lf fusion proteins c ...19921639793
the hamster transferrin receptor contains ser/thr-linked oligosaccharides: use of a lectin-resistant cho cell line to identify glycoproteins containing these linkages.we recently reported that the human transferrin receptor (tfr) contains o-linked galnac residues [1]. to investigate whether this modification is shared by transferrin receptors in other mammals, we investigated the glycosylation of tfr in hamster cells. to facilitate our analysis the lectin-resistant chinese hamster ovary (cho) cell line lec8 was used. these cells are unable to galactosylate glycoproteins, resulting in truncation of the ser/thr-linked oligosaccharides to a single residue of ter ...19921640050
expression of human transforming growth factor alpha by chinese hamster ovarian tumors in nude mice causes hypercalcemia and increased osteoclastic bone resorption.transforming growth factor alpha (tgf-alpha) is a polypeptide regulator of cell growth produced by many malignant tumors. it stimulates osteoclastic resorption in bone organ culture and osteoclast-like cell formation in marrow culture. to determine whether tumor production of tgf-alpha can cause hypercalcemia in vivo, we used chinese hamster ovarian (cho) cells transfected with the human tgf-alpha gene (tcho), which stably express and secrete tgf-alpha. we used nontransfected cho cells as contro ...19921642153
purification and characterization of furin, a kex2-like processing endoprotease, produced in chinese hamster ovary cells.furin, a mammalian homolog of the yeast kex2 protease, is associated with golgi membranes and is involved in cleavage of precursor proteins at sites marked by the arg-x-lys/arg-arg (rxk/rr) motif. we have recently shown that a furin mutant lacking the transmembrane domain can be secreted from cdna-transfected cells with proteolytic activity for the fluorogenic peptide t-butoxycarbonyl-arg-val-arg-arg-4-methylcoumarin-7- amide. in this study, we purified and characterized the recombinant furin fr ...19921644796
the insulin receptor functions normally in chinese hamster ovary cells after truncation of the c terminus.we studied the structure and function of the human insulin receptor (ir) and a mutant which lacked the last 43 amino acids of the beta-subunit (ir delta ct). this deletion removed tyrosine (tyr1322, tyr1316) and threonine (thr1336) phosphorylation sites. in chinese hamster ovary (cho) cells, insulin binding to the mutant receptor was normal, and [35s]methionine labeling indicated that both the ir and ir delta ct were processed normally; however, the beta-subunit of ir delta ct was 5 kda smaller ...19911645354
myristylation of the envelope glycoprotein of vesicular stomatitis virus.the envelope glycoprotein g of the indiana serotype of vesicular stomatitis virus was modified not only by palmitylation, but also by myristylation, both occurring at the carboxy-terminal segment. when infected chinese hamster ovary cells were grown in medium containing [3h]-myristate, the g protein and ga2, the membrane-anchoring fragment containing about 71 amino acids, were labeled. this was shown by immunoprecipitation of cell lysates or extracellular fractions of infected cultures. thin-lay ...19911645706
biologic activities of naturally occurring human insulin receptor mutations. evidence that metabolic effects of insulin can be mediated by a kinase-deficient insulin receptor mutant.we have studied insulin receptor-mediated signaling in chinese hamster ovary (cho) cell transfectants that expressed either of two naturally occurring mutant human insulin receptors: trp1200----ser1200 and ala1134----thr1134. compared with overexpressed normal human insulin receptors, both mutant receptors displayed normal processing and normal binding affinity; however, neither was capable of detectable insulin-stimulated autophosphorylation or tyrosine kinase activity toward endogenous (pp185) ...19911645719
structure of the human cytochrome c oxidase subunit vb gene and chromosomal mapping of the coding gene and of seven pseudogenes.subunit vb of mammalian cytochrome c oxidase (cox; ec is encoded by a nuclear gene and assembled with the other 12 cox subunits encoded in both mitochondrial and nuclear dna. we have cloned the gene for human cox subunit vb (cox5b) and determined the exon-intron structure by both hybridization analysis and dna sequencing. the gene contains five exons and four introns; the four coding exons span a region of approximately 2.4 kb. the 5' end of the cox5b gene is gc-rich and contains many h ...19911646156
mouse platelet-derived growth factor receptor alpha gene is deleted in w19h and patch mutations on chromosome 5.the mouse w19h mutation is an x-ray-induced deletion of more than 2 centimorgans on chromosome 5 encompassing the white spotting mutation w (encoded by the kit protooncogene), patch (ph), and recessive lethal (l) loci. the platelet-derived growth factor receptor alpha gene (pdgfra) like kit encodes a transmembrane receptor tyrosine kinase. by using mouse-chinese hamster somatic cell hybrids and haplotype analysis in interspecific backcross mice, mouse pdgfra was mapped to chromosome 5 in tight l ...19911647018
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