| biochemical approach to bovine leukemia. | many bovine leukemic lymphocytes produce virus particles when kept in survival cultures in eagle's minimum essential medium supplemented with 20 percent of inactivated fetal calf serum. virus particles equilibrate at a density of 1.16 g/ml in sucrose gradients and at a density of 1.12 g/ml in metrizamide gradients. simultaneous detection tests show that a high molecular weight rna-reverse transcriptase complex exists in these viruses. hybridizations between total rna from bovine leukemic lymphoc ... | 1975 | 52980 |
| interaction of rifamycins with mammalian nucleic acid polymerizing enzymes. | procedures were established for the isolation and partial purification of dna polymerase, rna polymerase and poly(a) polymerase activities from the cytoplasm and nuclei of nih-swiss mouse embryos. based on the elution pattern of these enzyme activities from deae-cellulose and phosphocellulose columns in tris-hcl buffer, ph 8.0, the apparent basicities of the enzymes can be arranged as follows: cytoplasmic(c) poly(a) polymerase greater than (c)dna polymerase beta greater than (c)dna polymerase al ... | 1976 | 63293 |
| bovine leukemia virus: an exogenous rna oncogenic virus? | short term cultures of bovine leukemic lymphocytes release virus particles with biochemical properties of rna oncogenic viruses. these particles, tentatively called bovine leukemia virus (blv) have a high molecular weight-reverse transcriptase complex and a density averaging 1.155 g/ml in sucrose solutions. molecular hybridizations between blv-3h cdna and several viral rnas show that blv is not related to mason-pfizer monkey virus (mpmv) simian sarcoma associated virus (ssv-1) feline leukemia vi ... | 1976 | 64382 |
| oncogenicity in marmosets of hl-23v, a type c oncornavirus isolated from human leukemic cells, and comparison with simian sarcoma virus type 1 (ssv-1/ssav-1). | type c virus produced by dog thymus cells (a7573) that were infected with virus (hl-23v), isolated from cultured leukocytes of an acute myelogenous leukemia patient, transformed marmoset and horse cells in vitro and induced virus-producing fibromas in marmosets. the tumors and transformed foci were indistinguishable morphologically from those induced by simian sarcoma virus, type 1 (ssv-1/ssav-1). hl-23v was indistinguishable from ssv-1/ssav-1 by immunofluorescence and neutralization tests, and ... | 1977 | 66319 |
| role of oncornaviruses in carcinoma of the prostate. | the existence of oncornavirus genetic information in human prostatic tissue was studied by assaying tissue extracts for products of viral gene expression (ie, the p30 antigen). tissue samples from patients with benign prostatic hyperplasia (bph) or prostatic carcinoma (cap) were assayed by the competetive radioimmunoassay. the competing antigens used were p30 proteins derived from the simian sarcoma virus type-1 (ssv-1) and the rauscher murine leukemia virus (rlv). of the 40 extracts tested, thr ... | 1977 | 68818 |
| characterization of a retravirus isolated from squirrel monkeys. | a new retravirus (smrv) isolated from a squirrel monkey, saimiri sciureus, has an mg2+-dependen reverse transcriptase and a buoyant density of 1.17 g/cm3 in sucrose and 1.21 g/cm3 in cesium chloride, similar to the mouse mammary tumor virus and the mason-pfizer monkey virus. the polypeptide patter of smrv as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis was distinct from the reported polypeptide patterns of known retraviruses. four major polypeptides of molecular weight ... | 1977 | 69728 |
| replication of primate oncornavirus ssv-1 on mrc-5 human diploid cells. | mrc-5 human diploid cells infected with simian sarcoma virus from woolly monkey (ssv-1) were not transformed but an efficient replication of non transforming silv was demonstrated. increase of virus reverse transcriptase activity paralleled cell replication during successive passages. preliminary results concerning the influence of viral infection on the life span and the karyotype of mrc-5 diploid cells will be reported and several implications of these findings discussed. | 1976 | 73483 |
| reverse transcriptase of foamy virus. purification of the enzymes and immunological identification. | reverse transcriptase from foamy virus, strain h4188 was estimated and purified. the enzyme has the following characteristics: 1. the reaction utilized preferentially oligo (dt) poly (ra) as a primer-template; however, the synthetic primer-template oligo (dt) poly (da) could also be used to some extent. 2. the reaction utilized oligo (dg) poly (rc) as a primer-template with very low efficiency. 3. the crude virus preparation had a detectable endogenous reaction using the four deoxyribonucleotide ... | 1977 | 74244 |
| [detection of common antigenic determinants in the envelopes of mammalian type d (mason--pfizer) and type c virions by using the virion precipitation reaction]. | immune sera to mason-pfizer virus (m-pmv) are capable of precipitating type c viruses of mice (nih-mulv, g-mulv, and to a lower degree r-mulv), cats (felv, rd-114), and monkeys (ssv-1, galv, bev). the immune sera to rd-114, bev, ssv-1 and galv viruses can precipitate m-pmv virions. the adsorption analysis suggests that cross-reactions between m-pmv, rd-114, nih-mulv, and g-mulv viruses depend on common virus-specific antigenic determinants in the envelopes of the virions. the relationship betwe ... | 1978 | 80888 |
| the use of trypan blue for counterstaining in the sepharose bead immunofluorescence test. the application of the test for the demonstration of primate retrovirus-specific antibodies and antigens. | the sepharose bead immunoflurorescence test was performed by counterstaining the beads with trypan blue. this results in a red staining of negative beads which allows an easy distinction from positive green-fluorescent beads. sepharose beads conjugated with viral proteins or antiviral antibodies were used to demonstrate mason-pfizer monkey virus (mpmw)- and simian sarcoma virus (ssv) - specific antigens or antibodies. the test shows a high sensitivity and specificity and needs a small amount of ... | 1978 | 86253 |
| serological analysis of an oncornavirus (pmf virus) detected in malignant permanent human cell lines. | immunodiffusion analysis of the pmf virus which was detected in malignant permanent human cell lines revealed positive reactions with antisera against the mason-pfizer monkey virus (mpmv). no cross-reactivity was demonstrated with murine leukemia virus (mulv), rat leukemia virus (ralv), hamster leukemia virus (halv), feline leukemia virus (felv), simian (woolly monkey) sarcoma virus (ssv-1) and mouse mammary tumor virus (mtv). the cross-reactive antigens of the pmf virus and the mpmv are conside ... | 1975 | 171892 |
| establishment of simian sarcoma virus, type 1 (ssv-1)-transformed non-producer marmoset cell lines. | simian sarcoma virus, type 1 (ssv-1)-transformed non-producer cell lines were established by infection of normal marmoset fibroblast cells (hf) with limiting dilutions of ssv-1. four focus-derived cell lines were identified as non-producers by assay of culture fluids for focus-forming activity and by the mixed culture cytopathogenicity test with xc cells. further studies failed to detect production of type-c virus by 3h-uridine labelling, reverse transcriptase assay or electron microscopy. the n ... | 1977 | 198378 |
| isolation of the major glycoprotein (gp 70) of simian sarcoma virus (ssv-1/ssav-1) in preparative quantities. | | 1977 | 201120 |
| characterization of a fetal calf serum-derived molecule reactive with human natural antibodies: its occurrence in tissue culture-grown type c rna viruses. | by means of a sensitive radioimmunoprecipitation (rip) assay, simian sarcoma virus-simian sarcoma-associated virus (ssv-ssav), purified from culture fluids of infected normal rat kidney (nrk) cells, was shown to acquire a surface antigen from serum used in the tissue culture medium. this antigen, which was acquired when serum from either fetal calf, horse, swine, rabbit, or chicken origin was used, accounted for a substantial portion (but not all) of the total precipitating activity exhibited by ... | 1978 | 202656 |
| cell-mediated immune response to simian oncornavirus antigens in pregnant women. | tritiated thymidine incorporation into lymphocytes of 118 adult women was studied in the presence of mitomycin c-treated cells prepared from cell lines continuously producing mason-pfizer monkey virus (mpmv), baboon c-particle virus, or simian sarcoma virus (ssv) and in the presence of control cell lines documented for the absence of oncornaviruses. at the end of pregnancy, women who had 5-9 pregnancies showed a high frequency (53%) of specific positive responses to cells with mpmv antigens. the ... | 1978 | 203708 |
| immunity to antigens associated with primate c-type oncoviruses in pregnant women. | cell-mediated and humoral immune responses against antigens associated with primate c-type oncoviruses were evaluated in humans by microcytotoxicity and radioimmunoprecipitation assays. five of six women tested sequentially during pregnancy developed selective cell-mediated reactivity against baboon endogenous virus (bev)--infected human fibroblasts. responsiveness peaked during the second and third trimesters and corresponded temporally with elevated antibody levels to bev antigens. similar cel ... | 1978 | 204010 |
| oncogenicity of the c-type virus hl-23v in marmosets and characterization of virus isolated from an hl-23v-induced marmoset tumor: comparison with simian sarcoma virus type 1. | dog thymus cells chronically infected with hl-23v, a c-type virus isolated from human acute myelogenous leukemia cells, produced both transforming and nontransforming virus indistinguishable from simian sarcoma virus type 1 (ssv-1/ssav-1) and induced fibromas in newborn marmosets. all inoculated marmosets developed anti-hl-23v antibodies. a cell line established from a tumor biopsy produced transforming virus identical to ssv-1 and hl-23v at early passages. however, at later passages the cell li ... | 1978 | 205850 |
| syncytia formation of human transformed cell lines by simian sarcoma virus type i (ssv-i/ssav-i). | human cells derived from malignant tumors (hela, hep-2 and kb) and human cells transformed by tumor viruses (kcand rsb) formed syncytia by simian sarcoma virus type i (ssv-i/ssav-i), but human diploid or non-transformed cells (wi-38, hel and hec) did not. | 1979 | 224650 |
| elevated titer of antibodies to simian sarcoma virus envelope antigen (gp70) and normal response to influenza virus in untreated danish hodgkin's patients. | untreated danish hodgkin's disease (hd) patients and paired age- and sex-matched controls were tested for serum antibodies to epstein-barr virus (ebv), six strains of influenza virus and simian sarcoma virus/simian sarcoma-associated virus [ssv(ssav)] antigens. hd sera showed significantly elevated titers against ebv and both increased incidence and mean titer of antibodies to the envelope glycoprotein of ssv(ssav), whereas testing against the influenza viruses revealed no differences between hd ... | 1979 | 225281 |
| retinoic acid inhibition of serum-induced c-fos transcription in a fibrosarcoma cell line. | we investigated the mechanism by which retinoic acid causes growth arrest and flat reversion of ssv-nrk, simian sarcoma virus-transformed normal rat kidney cells. northern analysis revealed that both chronic (7 days) and acute (6 h) retinoic acid treatment of serum-stimulated ssv-nrk cells caused a 6-fold decrease in c-fos mrna levels. in addition, nuclear run-on experiments showed that retinoic acid regulated c-fos expression in ssv-nrk cells at the transcriptional initiation level. attenuation ... | 1992 | 1568207 |
| simian sarcoma virus transformation of normal rat kidney fibroblasts is associated with markedly increased basic fibroblast growth factor expression. | transformation of normal rat kidney fibroblasts (nrk) by the simian sarcoma virus (ssv) occurs as a result of expression of p28v-sis, a homologue of platelet-derived growth factor-b chain. chromatographic separation revealed that the bulk (85%) of the mitogenic activity in ssv-transformed nrk cells was not due to p28v-sis but rather two distinct endothelial cell growth factors that eluted off heparin-sepharose between 1 and 2 m nacl. protein purification and northern blot analysis revealed that ... | 1991 | 1656977 |
| imbalanced expression of cellular nuclear oncogenes caused by v-sis/pdgf-2. | two murine cell lines that overexpress v-sis/pdgf-2 were used to study the mechanism of cell transformation by ssv (simian sarcoma virus). in contrast to the parental cells that are phenotypically normal and serum-dependent for growth, v-sis-overexpressing cells grow in pdgf-free plasma medium, are unable to enter the g0 state and are highly tumorigenic. analysis of the expression of some growth factor-induced early response genes in v-sis-overexpressing cells revealed: (a) high and constitutive ... | 1991 | 1923519 |
| antibodies to retroviruses of types c and d in female patients with benign and malignant mammary tumours. | the sera of women with benign and malignant mammary tumours were investigated for the presence of antibodies to structural proteins of retroviruses types c and d by indirect immunoenzyme assay (elisa) and immunoblotting. among 89 sera tested 5 reacted with the rd-114 protein, 2 with ssv, m-7, and bovine leukaemia virus proteins. none serum reacted with mouse mammary tumour virus proteins. on the basis of these results we conclude that the expression of antibodies to structural retrovirus protein ... | 1990 | 1975721 |
| characterization of the sugarcane streak agent as a distinct geminivirus. | the relationship between maize streak virus and the geminivirus causing streak in sugarcane was investigated. the dna of sugarcane streak virus does not cross-hybridize detectably with that of maize streak virus and vice versa. restriction mapping of native replicative form viral dna (genome size 2.7 kb) and of cloned viral dna, combined with limited sequencing and estimated dna sequence divergence, showed that sugarcane streak virus is as unrelated to maize streak virus and digitaria streak vir ... | 1991 | 2016148 |
| s71 is a phylogenetically distinct human endogenous retroviral element with structural and sequence homology to simian sarcoma virus (ssv). | human endogenous retroviral element s71 had previously been shown to contain gag- and pol-related regions and a 3' ltr-like sequence. the nucleotide sequence of s71 was determined and compared with the corresponding regions of ssv and its helper virus ssav. the 1.48-kb s71 gag region consists of matrix protein p15 (ma)-, capsid protein p30 (ca)-, and nucleocapsid protein p10 (nc)-related sections and the 1.82-kb pol region of tether, rnase h (rh), and endonuclease/integrase (in) sections. the s7 ... | 1990 | 2152993 |
| intracellular turnover, novel secretion, and mitogenically active intracellular forms of v-sis gene product in simian sarcoma virus-transformed cells. implications for intracellular loop autocrine transformation. | in simian sarcoma virus (ssv)-transformed cells (ssv-nrk, ssv-nih 3t3, and ssv-np1 cells), the v-sis gene product was synthesized as a 36-kda glycopolypeptide with one endoglycosidase (endo) h-sensitive oligosaccharide chain and formed a dimer (p72) with a half-time of less than 5 min. p72 was proteolytically processed to generate sequentially p68 and p58 in the endoplasmic reticulum/golgi complex, p44 in the post-golgi complex compartments, and p27 in an endosomal/lysosomal compartment. a porti ... | 1990 | 2153139 |
| structural and functional aspects of platelet-derived growth factor and its receptors. | platelet-derived growth factor (pdgf) is a dimeric molecule that exists as homodimers or heterodimers of related polypeptide chains (a and b). two types of pdgf receptor have been identified. the pdgf alpha-receptor binds all three isoforms with high affinity whereas the beta-receptor binds only pdgf-bb with high affinity, pdgf-ab with low affinity and does not appear to bind pdgf-aa. the alpha- and beta-receptors are structurally related, each having an intracellular protein tyrosine kinase dom ... | 1990 | 2164910 |
| detection and typing of maize streak virus and other distantly related geminiviruses of grasses by polymerase chain reaction amplification of a conserved viral sequence. | the application of the polymerase chain reaction dna amplification technique to the detection and typing of isolates of maize streak virus (msv) and other related geminiviruses of grasses is described. the oligonucleotide primers used for amplification were 17-mers which contained a number of degeneracies. an approximately 250 base pair fragment was amplified from all geminivirus-infected grass and cereal samples tested. the amplification reaction was specific, working down to a concentration of ... | 1990 | 2254750 |
| invasiveness and chemotactic activity of oncogene transformed nih/3t3 cells. | the role of oncogenes in the acquisition of invasive and metastatic capabilities is controversial. interactions with basement membranes are critical in the process of tumor invasion and metastasis. we compared the ability of 3t3 cells transformed by oncogenes involved in various stages of signal transduction to invade a reconstituted basement membrane in vitro and to grow in a three dimensional basement membrane gel (matrigel). cell lines transformed by various oncogenes and oncoviruses: v-sis ( ... | 1990 | 2334141 |
| biochemical and immunological characterization of suncus murinus mammary tumor virus dna polymerase. | enzymological properties of the rna-directed dna polymerase associated with the suncus murinus mammary tumor virus (sm-mtv) was investigated and its antigenic relatedness to other retroviral dna polymerases was examined. the enzyme exhibited higher activity in the presence of mg2+ than in the presence of mn2+ with endogenous rna as well as with almost all of the synthetic template x primers tested. mg2+ was also effective with poly(2'-o-methylcytidylate) x oligodeoxyguanylate which was known to ... | 1986 | 2417416 |
| platelet-derived growth factor induces phosphorylation of a 64-kda nuclear protein. | the platelet-derived growth factor (pdgf) stimulated the phosphorylation of a nuclear protein of 64 kda (pp64) in nuclei of nontransformed normal rat kidney (nrk) cells. low levels of phosphorylation of pp64 were observed in nuclei of serum-starved nrk cells. fetal calf serum (fcs), pdgf, and homodimeric v-sis and pdgf a-chain protein enhanced the incorporation of 32p into pp64 over 4-fold within 30 min and over 8-fold within 2 h of exposure of nrk cells to the growth factors. in contrast, const ... | 1989 | 2463244 |
| analysis of a transformed cell line using antisense c-fos rna. | simian sarcoma virus (ssv)-infected nih-3t3 cells (ssv-nih-3t3), express a homologue of platelet-derived growth factor, (pdgf) a powerful inducer of the c-fos gene. we have used these cells to test the hypothesis that autocrine stimulation by pdgf-like molecules leads to c-fos expression which is functional in the transformed phenotype. we have transfected ssv-nih-3t3 cells with a c-fos antisense-rna expression vector, psvsof, or control plasmids. psvsof-transfected cells exhibit markedly decrea ... | 1988 | 2468566 |
| inhibition of glycosylation processing alters the growth parameters of cells transformed by the oncogene of simian sarcoma virus. | normal rat kidney (nrk) cells transformed by the v-sis oncogene of simian sarcoma virus (ssv) were treated with the glucosidase i inhibitor castanospermine. the inhibitor did not change cell morphology, but specific growth parameters such as serum- and anchorage-independence were lost. | 1989 | 2539799 |
| v-sis gene (ssv) is expressed transiently and independently of v-gag (ssav) after infection of fibroblasts with ssv/ssav. | to investigate the mechanism of cell transformation by the retroviral v-sis gene, we examined the mode of its mrna expression after infection of primate fibroblasts with simian sarcoma virus (ssv/ssav). surprisingly transient expression of the 5.3 kb transcript of v-sis was detected between day two and four after infection. addition of cycloheximide did not reverse the down-regulation of v-sis expression. suramin, which uncouples the pdgf receptor complex, had no effect on the pattern of v-sis e ... | 1989 | 2550873 |
| basic fibroblast-like growth factor is present in the conditioned medium of simian sarcoma virus transformed nrk cells. | the conditioned medium of simian sarcoma virus (ssv)-transformed nrk cells contains at least two activities that down regulate the epidermal growth factor receptor. to identify these activities, we analyzed the medium for the presence of factors both related to and distinct from the v-sis oncogene product. fractionation of the conditioned medium from ssv-transformed nrk cells by chromatography on heparin-sepharose yielded two active fractions capable of inhibiting egf binding. the first componen ... | 1989 | 2556126 |
| properties of retroviral protease responsible for gag precursor cleavage. | friend leukemia virus (flv) particles contain a protease which cleaves not only its own gag precursor but also the gag polyprotein of simian sarcoma virus (ssv). to determine the localization of the enzyme within the virion, purified virus was fractionated. according to our studies most of the proteolytic activity is located within the retroviral core. since ionic detergents inhibit the protease, heat treatment was found to be the most effective way to release the molecule from the virus particl ... | 1989 | 2672563 |
| [isolation and characteristics of antibodies against synthetic fragments of oncoproteins. i. antiserum against the transforming protein p28sis of simian sarcoma virus]. | to generate the antibodies to the transforming protein (p28sis) of simian sarcoma virus (ssv), the rabbits were immunized with peptides, corresponding to 200-206 and 201-210 sequences of p28sis, conjugated with protein carriers by different ways. the synthesis of peptides was carried out by the classical techniques in solution by using the benzyl type side protecting groups. antibody titres against peptides were determined by elisa and protein specificity by radioimmunoprecipitation and immunobl ... | 1987 | 2821385 |
| platelet-derived growth factor: roles in normal and v-sis transformed cells. | platelet-derived growth factor (pdgf) is the most potent mitogenic protein in human serum. the normal roles of this protein may relate to its potent mitogenic properties and its activities in directed cell migration and at sites of wounds. pdgf is a heterodimeric protein of approximately 30,000 molecular weight; one polypeptide chain of pdgf is highly homologous to the predicted amino acid sequence of p28v-sis, the putative transforming protein of simian sarcoma virus (ssv), suggesting a major r ... | 1985 | 2824043 |
| platelet-derived growth factor/sis in normal and neoplastic cell growth. | platelet-derived growth factor (pdgf) is the major growth factor in serum and a potent mitogen for cells mesenchymal origin. it is a highly basic heterodimeric protein with a molecular mass of approximately 30 kda and binds to a cell surface receptor with high affinity. the amino acid sequence of pdgf revealed sequence homology to the v-sis gene product of simian sarcoma virus (ssv), a transforming retrovirus. characterization of cells transformed by ssv has revealed pdgf-related proteins in sub ... | 1987 | 2824537 |
| identification and purification of pdgf/sis-like proteins from nuclei of simian sarcoma virus-transformed fibroblasts. | the platelet-derived growth factor (pdgf) is a potent mitogen for cells derived from mesenchyme and is highly related to the transforming protein of the simian sarcoma virus (ssv), p28v-sis. both pdgf and p28v-sis appear to initiate dna synthesis and cell proliferation through an interaction with pdgf cell surface receptors but the identity of the pdgf induced signals which are recognized within the nucleus is unknown. it has been suggested that pdgf is directly transported to the nucleus althou ... | 1988 | 2835737 |
| highly glycosylated pdgf-like molecule secreted by simian sarcoma virus-transformed cells. | antiserum to human platelet-derived growth factor (pdgf) recognized a simian sarcoma virus transformation-specific glycopeptide, now termed gp200sis, thereby establishing an immunological relationship between pdgf and this highly glycosylated molecule. the same antibodies as well as an antiserum against ssv-np cells reacted with isolated gp200sis after immunoprecipitation, sds-page, and electroelution. in analogy to pdgf, the gp200sis protein backbone is shown here to consist of disulfide-linked ... | 1988 | 2835858 |
| a high-molecular-weight pdgf-like factor secreted by v-sis transformed cells leads to growth stimulation and transformation. | transformation by the v-sis containing simian sarcoma virus (ssv) is believed to be mediated by constitutive production of a platelet-derived growth factor (pdgf)-like molecule and its interaction with the pdgf receptor. ssv-transformed nonproducer nrk cells release into their tissue culture supernatant a high-molecular-weight factor (150-300 kda) with biological activities closely resembling those of human pdgf. the partially purified high-molecular-weight factor competes with 125i-pdgf for rec ... | 1988 | 2840622 |
| purification and chemical and immunological characterization of avian reticuloendotheliosis virus gag-gene-encoded structural proteins. | five gag-gene-encoded structural proteins, designated p12, pp18, pp20, p30, and p10 were purified from replication-competent avian reticuloendotheliosis-associated virus (rev-a) by high-performance liquid chromatography complemented with chloroform-methanol extraction and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. based on amino acid composition and nh2- and cooh-terminal sequence analysis p12, pp18, p30, and p10 are distinct from one another, whereas pp20 is likely identical to ... | 1985 | 2982236 |
| serum antibody reacting with placental syncytiotrophoblast in sera of patients with autoimmune diseases--a possible relation to type c rna retrovirus. | this study reports the immunohistological detection of serum antibody reacting with the basal aspect of syncytiotrophoblast of human chorionic villi, where ssav/galv (simian sarcoma associated virus/gibbon ape lymphoma virus) type c retrovirus p30 related antigen was observed by an indirect immunofluorescent method using monospecific antibodies against ssav p28 and galv p29. the immunoglobulin class of this antibody activity called 'the anti-basal aspect of syncytiotrophoblast (anti-bast)', was ... | 1985 | 2990781 |
| in vitro mutagenesis of the v-sis transforming gene defines functional domains of its growth factor-related product. | the polypeptide sequence of the v-sis transforming gene product of simian sarcoma virus (ssv) can be divided into four regions that are likely to represent structural domains of the protein. mutations were generated in the ssv nucleotide sequence to assay the extent or function of each of these regions. the results indicate that the helper virus-derived amino-terminal sequence as well as a core region homologous to polypeptide chain 2 of platelet-derived growth factor (pdgf) are required for the ... | 1985 | 2991916 |
| the v-sis/pdgf-2 transforming gene product localizes to cell membranes but is not a secretory protein. | the v-sis transforming gene encodes the woolly monkey homologue of human platelet-derived growth factor (pdgf) polypeptide 2. after its synthesis on membrane bound polyribosomes, the glycosylated precursor dimerizes in the endoplasmic reticulum and travels through the golgi apparatus. at the cell periphery, the precursor is processed to yield a dimer structurally analogous to biologically active pdgf. small amounts of two incompletely processed forms are detectable in tissue culture fluids of si ... | 1985 | 2992941 |
| antibodies against platelet-derived growth factor inhibit acute transformation by simian sarcoma virus. | a clue to the molecular mechanism of neoplastic transformation was provided by the finding of a near identity in amino-acid sequence between the platelet-derived growth factor (pdgf) b-chain and a region in the transforming protein, p28sis, of simian sarcoma virus (ssv), an agent that causes sarcomas and gliomas in experimental animals. this finding infers a direct link between the molecular biology of normal mitogenesis and oncogenesis since it suggests that the transforming activity of ssv is ... | 1985 | 2995828 |
| evidence that the v-sis gene product transforms by interaction with the receptor for platelet-derived growth factor. | a scheme for partial purification of biologically active v-sis-coded protein from cells transformed with simian sarcoma virus (ssv) has made possible a functional comparison of the transforming protein with platelet-derived growth factor (pdgf). the ssv-transforming gene product is capable of specifically binding pdgf receptors, stimulating tyrosine phosphorylation of pdgf receptors, and inducing dna synthesis in quiescent fibroblasts. each of these activities was specifically inhibited by antib ... | 1985 | 2996133 |
| simian sarcoma virus-encoded gag-related protein: in vitro cleavage by friend leukemia virus-associated proteolytic activity. | the simian sarcoma virus (ssv) encodes a gag-related 65,000-da protein (ssv p65) which is not processed in ssv nonproducer cells (ssv-np cells) (h.-j. thiel, t. j. matthews, e. m. broughton, k. j. weinhold, d. p. bolognesi, t. graf, and h. beug (1981a), virology 114, 124-131). in order to cleave ssv p65, retroviral particles containing this antigen were incubated with extracts from the heterologous helper virus friend leukemia virus (flv). superinfection of ssv-np cells by flv has been previousl ... | 1985 | 2997999 |
| transformation of diploid human fibroblasts by dna transfection with the v-sis oncogene. | the simian sarcoma virus (ssv) oncogene (v-sis) has a high degree of homology to the cellular gene coding for the b peptide of human platelet-derived growth factor (pdgf), a potent fibroblast mitogen. the cellular homolog of v-sis is activated in some mesenchymal human tumors and cell lines derived from them. to determine the phenotype produced by v-sis in diploid human fibroblasts, we constructed plasmids containing the ssv provirus and drug-resistance markers and transfected them into early-pa ... | 1986 | 3015989 |
| the phenotypic characteristics of simian sarcoma virus-transformed human fibroblasts suggest that the v-sis gene product acts solely as a pdgf receptor agonist in cell transformation. | previous studies have indicated that the oncogene v-sis of simian sarcoma virus (ssv) encodes a growth factor that is structurally and functionally similar to platelet-derived growth factor (pdgf). in the present investigation we have analysed the phenotypic characteristics of human foreskin fibroblasts transformed by ssv. it was found that the pdgf receptors were extensively down-regulated. this finding is consistent with a high, local, extracellular concentration of a pdgf-like factor, synthes ... | 1986 | 3017700 |
| production of transforming growth factors by simian sarcoma virus-transformed cells. | cellular transformation of normal rat kidney (nrk) cells by simian sarcoma virus (ssv) results in a complete loss of the cellular requirement of externally added polypeptide growth factors for proliferation. moreover, ssv-transformed nrk cells have a strongly reduced ability to bind both external platelet-derived growth factor and epidermal growth factor, when compared to nontransformed nrk cells. analysis of serum-free medium conditioned by ssv-transformed nrk cells shows that this cell line se ... | 1987 | 3028611 |
| ultrastructural localization of a platelet-derived growth factor/v-sis-related protein(s) in cytoplasm and nucleus of simian sarcoma virus-transformed cells. | the subcellular distribution of v-sis-related protein(s) was analyzed in three simian sarcoma virus (ssv)-transformed cell lines with immunofluorescence and protein a-gold labeling techniques using rabbit polyclonal anti-platelet-derived-growth factor (pdgf) antisera. antigenically reactive proteins were recognized in subcellular organelles related to protein synthesis and processing, including polyribosomes, endoplasmic reticulum, and the golgi apparatus, as well as on the cytoplasmic surface o ... | 1987 | 3031678 |
| a human osteosarcoma cell line secretes a growth factor structurally related to a homodimer of pdgf a-chains. | platelet-derived growth factor (pdgf), as purified from fresh human platelets, is a protein of relative molecular mass (mr) 30,000 composed of two disulphide-linked subunit chains of similar size, named a and b (ref. 1). the dimer structure of pdgrf seems to be important for its biological effects, as reduction irreversibly inactivates the factor; it is not known, however, whether pdgf exists as a heterodimer or as a mixture of homodimers. amino-acid sequence analysis has revealed that the a- an ... | 1986 | 3456080 |
| possible positive autocrine feedback in the prereplicative phase of human fibroblasts. | the growth of normal diploid fibroblasts is generally thought to be tightly controlled by exogenous growth factors such as platelet-derived growth factor (pdgf) and epidermal growth factor (egf). subversion of a growth factor pathway at a regulatory point is considered to be a key event in neoplastic transformation and tumorigenesis. thus, simian sarcoma virus has acquired the gene encoding the b-chain of pdgf and there is direct experimental proof that ssv-transformation is mediated by a pdgf-l ... | 1987 | 3497351 |
| the sis gene and pdgf. | the aberrant expression of a protein that is involved in normal growth regulatory pathways can cause cell transformation. one of the best examples of this phenomenon is the transformation of fibroblasts by the simian sarcoma virus (ssv). an oncogene (v-sis) of this virus encodes a protein whose amino acid sequence is highly homologous to one of the subunits of a mesenchymal cell mitogen, platelet-derived growth factor (pdgf). how does expression of the v-sis or related genes transform cells? cle ... | 1986 | 3536086 |
| platelet-derived growth factor as a mediator of normal and neoplastic cell proliferation. | human platelet-derived growth factor is the major mitogen in serum for connective-tissue-derived cells in culture. the factor is 30,000 mol. wt protein composed of two disulphide-linked polypeptide chains, named a and b. the b-chain is virtually identical to part of the transforming protein of simian sarcoma virus (ssv), implying that ssv-transformation is mediated by a pdgf-like growth factor. this notion is supported by the finding that specific as well as nonspecific inhibitors of pdgf-action ... | 1986 | 3543531 |
| cdna clones reveal differences between human glial and endothelial cell platelet-derived growth factor a-chains. | human platelet-derived growth factor (pdgf) is a potent mitogenic polypeptide which is believed to be a heterodimer of a- and b-chains stabilized by interchain disulphide bonds. the b-chain of pdgf is encoded by the c-sis gene, the normal cellular homologue of the transforming gene of the simian sarcoma virus (ssv). cdna clones of the b-chain from both normal and transformed cells have mutually consistent dna sequences. recently, an a-chain cdna clone (d-1) was isolated from a transformed human ... | 1987 | 3614363 |
| hodgkin's disease: in vitro susceptibility of skin fibroblasts to infection with virus and to lysis by autologous lymphocytes. | fibroblast cultures established from the skin of 16 untreated stage 1 and stage 2 hodgkin's patients (hd) and 60 healthy controls were studied in their 3rd, 4th and 5th in vitro passage. hd cultures were similar to control cultures with respect to transformation with simian sarcoma virus (ssv) and sv40 and with respect to interferon release. hd cultures, however, showed a depressed replication of both herpes simplex virus (hsv) type 1 and type 2. preliminary evidence for enhanced immune interact ... | 1983 | 6085523 |
| simian sarcoma virus transformation-specific glycopeptide: immunological relationship to human platelet-derived growth factor. | the simian sarcoma virus transformation-specific glycopeptide (ssv-trsgp) represents a proteoglycan which is released from ssv-transformed cells and can be detected by an autologous goat serum against ssv nonproducer cells (ssv-np serum) (h.-j. thiel, r. hafenrichter, and b. gregor, 1984, virology 134, 138-147). this antiserum has now been shown to react also with human platelet-derived growth factor (pdgf). antiserum to pdgf precipitated a glycosylated molecule from the tissue culture supernata ... | 1984 | 6087551 |
| transforming protein of simian sarcoma virus stimulates autocrine growth of ssv-transformed cells through pdgf cell-surface receptors. | simian sarcoma virus-transformed nih 3t3 (ssv-nih 3t3) and ssv-nrk cells secrete a potent growth-promoting activity identical with the platelet-derived growth factor (pdgf) in mitogenic assays. the secreted activity is blocked by anti-pdgf antisera and competes with 125i-pdgf for receptor binding, suggesting that the secreted protein is the transforming protein of ssv, p28v-sis, or its processed product. secreted p28v-sis appears to stimulate autocrine cell growth of ssv-transformed cells becaus ... | 1984 | 6091918 |
| blockade of autocrine stimulation in simian sarcoma virus-transformed cells reverses down-regulation of platelet-derived growth factor receptors. | the viral (v)-sis oncogene encodes a protein (p28sis) that is structurally homologous to platelet-derived growth factor (pdgf). we have shown that simian sarcoma virus (ssv)-transformed cells containing the v-sis oncogene release a mr 20,000 substance that is recognized by antisera to synthetic peptide sequences contained in p28sis. medium conditioned by ssv-transformed cells competes with 125i-labeled pdgf for specific pdgf receptor sites, initiates dna synthesis, and stimulates tyrosine phosph ... | 1984 | 6095298 |
| protamine inhibits platelet derived growth factor receptor activity but not epidermal growth factor activity. | protamine sulfate blocked 125i-pdgf binding to its specific physiological receptor on swiss mouse 3t3 cells. reduced 125i-pdgf binding in the presence of protamine sulfate correlated directly with a protamine sulfate dose-dependent decrease in the pdgf-dependent incorporation of [3h]-thymidine into 3t3 cells and a decreased pdgf-stimulated tyrosine-specific protein kinase activity in isolated membrane preparations of 3t3 cells. protamine sulfate blocked 125i-pdgf binding to simian sarcoma virus ... | 1984 | 6099364 |
| in vitro susceptibilities of normal human skin fibroblasts to oncoviruses, and the decreased susceptibility to hsv of fibroblasts from untreated hodgkin's patients. | fibroblast cultures established from the skin of 56 healthy controls and 15 untreated stages i and ii hodgkin's patients (hd) were studied in their 3rd, 4th and 5th in vitro passage with respect to transformation with simian sarcoma virus (ssv) and sv40 and with respect to replication of herpes simplex virus (hsv) types 1 and 2, pox virus and interferon release. susceptibility to the 5 viruses varied independently, except for an inverse correlation between susceptibility to ssv and hsv. hd cultu ... | 1981 | 6166307 |
| demonstration of antigenic cross-reactivity between simian sarcoma virus (ssv) and mason-pfizer monkey virus (mpmv): brief report. | | 1981 | 6171238 |
| characterization of antigens in ssv nonproducer cells. | an autologous antiserum against simian sarcoma virus (ssv) nonproducer cells (ssv-np cells) was characterized by radioimmunoprecipitation. it reacts specifically with two different molecules in ssv-np cells, a ssv transformation-specific glycoprotein (ssv trs-gp) and p65, which probably represents a modified gag-precursor. | 1981 | 6172323 |
| synthesis of a viral protein with molecular weight of 30,000 (p30) by leukemic cells and antibodies cross-reacting with simian sarcoma virus p30 in serum of a chronic myeloid leukemia patient. | we studied a patient with a philadelphia chromosome-positive chronic myeloid leukemia, who died in relapse after multiple transfusions and grafting with bone marrow from his monozygotic twin brother (referred to as "donor" in this paper). we present data indicating that this patient may have had a retro-virus infection that this virus is related to the group of exogenous primate type c retroviruses. antibodies to simian sarcoma virus (ssv) m.w. 30,000 protein (p30) but not endogenous feline viru ... | 1982 | 6173117 |
| antisera to a synthetic peptide of the sis viral oncogene product recognize human platelet-derived growth factor. | it has recently been reported that the sequences of the sis oncogene of simian sarcoma virus (ssv) and of human platelet-derived growth factor (pdgf) are very similar, establishing the most solid link yet between the mitogenic actions of growth factors and the transforming proteins of retroviruses. to investigate molecular mechanisms of transformation i have produced antisera against synthetic peptides corresponding to segments of the protein sequences predicted by the nucleotide sequences of vi ... | 1984 | 6197658 |
| partial characterization of a transformation-specific glycopeptide in ssv-np cells. | an autologous antiserum against simian sarcoma virus-infected nonproducer cells (ssv-np cells) recognized a ssv transformation-specific glycopeptide (ssv-trsgp) [h.-j. thiel, t.j. matthews, e.m. broughton, a.m. butchko, and d.p. bolognesi (1981) virology 112, 642-650]. gel filtration of this component on a sephacryl s-200 column indicated an apparent molecular weight at about 200,000 (d). this antigen represented a proteoglycan-like molecule, as evidenced by the size of glycopeptides after prona ... | 1984 | 6200991 |
| [detection of antigenic determinants of the major structural proteins of various mammalian type c retroviruses in the leukocytes of patients with hemoblastoses and in healthy donors by the elisa method]. | using the enzyme-labelled antibodies it was shown that extracts from leukocytes of patients with leukemias and healthy donors contain antigenic determinants related to major virus protein of mammalian c type oncornaviruses ssv/ssav, baev, felv and rlv. the highest antigen activity in patients was detected in the feline leukemia (felv) system, and the least one--in the system of murine leukemia (rlv). common antigenic determinants of major virus protein of the viruses under study were detected in ... | 1984 | 6209091 |
| search for mammalian type-c retrovirus polypeptides on infected animal cells and human tumor cell lines using interspecies-reacting antibodies. | cells producing endogenous and exogenous type-c retroviruses of murine, feline and primate origin were evaluated for expression of those virus-specific cell-surface antigens which cross-react with antibodies to interspecies determinants of mammalian type-c viral polypeptides. surface polypeptides of cells replicating endogenous and exogenous type-c retroviruses were iodinated by the lactoperoxidase method. labelled antigens were immunoprecipitated and analyzed in polyacrylamide gel electrophores ... | 1980 | 6244200 |
| specificity of human antibodies to oncovirus glycoproteins: recognition of antigen by natural antibodies directed against carbohydrate structures. | antibodies in human sera from healthy individuals were shown to be reactive with highly purified 70,000-dalton envelope glycoprotein (gp70) of the simian sarcoma virus-simian sarcoma-associated virus (ssv-ssav) complex in radioimmunoprecipitation assays under certain conditions. the specificity of the reaction was analyzed in absorption tests with normal human serum proteins, assays of viral gp70 antigenicity after exposure to exo- and endoglycosidases or trypsin, and carbohydrate hapten inhibit ... | 1980 | 6246496 |
| isolation of a virus closely related to gibbon ape leukaemia virus from cells infected with virus (hl-23v) released by human leukaemic cells. | canine thymus cells infected with virus (hl-23v) produced by human acute myelogenous leukaemia cells in culture were shown in previous reports to produce transforming and non-transforming type c virus similar or identical to the simian sarcoma virus complex ssv(ssav) and to induce tumours in marmoset monkeys (bergholz et al. 1977a). in these earlier studies the appearance of breakthrough foci at low dilutions of antiserum in neutralization tests with high-titred anti-ssv(ssav) serum suggested th ... | 1980 | 6247431 |
| induction of syncytia by simian sarcoma virus type i (ssv-i/ssav-i) in several human transformed cell lines. | simian sarcoma virus type i (ssv-i/ssav-i) induced syncytia formation in human cells derived from malignant tumors (kb, hep-2 and hela cells) and human cells transformed by tumor viruses (rsa, rsb and kc cells) as well as rat xc cells. however, ssv-i/ssav-i did not induce syncytia formation in human cells derived from normal embryos (wi-38, hel and hec). syncytia-inducing activity of ssv-i/ssav-i was neutralized by anti-ssv-i/ssav-i serum, indicating that syncytia formation was ssv-i/ssav-i medi ... | 1980 | 6250927 |
| molecular cloning of integrated simian sarcoma virus: genome organization of infectious dna clones. | the integrated form of simian sarcoma virus (ssv) was molecularly cloned in the charon 16a strain of bacteriophage lambda. in transfection analysis, the recombinant viral dnas demonstrated the ability to transform cells in tissue culture at high efficiency. such transformants possessed typical ssv morphology, expressed simian sarcoma associated virus (ssav) gag gene products in the absence of virus release, and released ssv after superinfection with a type c helper virus. a physical map of the 5 ... | 1981 | 6265924 |
| molecular cloning and comparative analyses of the genomes of simian sarcoma virus and its associated helper virus. | closed circular viral dna of simian sarcoma virus (ssv) and simian sarcoma-associated virus (ssav) obtained from acutely infected dog cells was purified on preparative agarose gels, cleaved with ecori, and cloned in the phage lambda vector charon 21a. the cloned 9-kilobase ssav genome (b11) has the same restriction map as the bulk of the unintegrated linear ssav dna intermediate. heteroduplex analysis between an ssv clone (lambda-c60) and an ssav clone (lambda-b11) showed two substitution loops ... | 1981 | 6267588 |
| [phorbol ester-induced expression of primate retroviruses (author's transl)]. | addition of the tumor promoter 12-0-tetradecanoyl-phorbol-13-acetate (tpa) to the growth medium of certain human cell cultures persistently infected with simian retroviruses of type c (baev, ssv) or type d (mpmv) or a human cell line-derived type d isolate (pmfv), respectively, resulted in a considerable but transient stimulation of virus production. enhanced virus expression was paralleled by striking morphological alterations of the cells. among four infected cell types tested so far, ony one ... | 1981 | 6279052 |
| deletions of specific regions of the simian sarcoma-associated virus genome are found in defective viruses and in the simian sarcoma virus. | extrachromosomal dna was isolated from tissue culture cells that were acutely infected with simian sarcoma virus (ssv) and its associated helper (simian sarcoma-associated virus [ssav]). two sizes of closed circular viral genomic dna intermediates were isolated, cleaved at the single ecori site, and ligated to the charon 21a phage lambda vector. cloned molecules of the larger size all represented the full-length (9.0-kilobase [kb]) ssav molecule. a heterogeneous group of clones was derived from ... | 1982 | 6281470 |
| expression of cellular homologues of retroviral onc genes in human hematopoietic cells. | total cellular poly(a)-enriched rna from a variety of fresh human leukemic blood cells and hematopoietic cell lines was analyzed for homology with molecularly cloned dna probes containing the onc sequence of abelson murine leukemia virus (ab-mulv), harvey murine sarcoma virus (ha-musv), simian sarcoma virus (ssv), and avian myelocytomatosis virus strain mc29. results with the fresh blood cells paralleled those obtained with the cell lines. with ab-mulv and ha-musv, multiple rna bands were visual ... | 1982 | 6283530 |
| nucleotide sequence of the transforming gene of simian sarcoma virus. | the sequence of the transforming region of simian sarcoma virus (ssv) has been determined by using molecularly cloned viral dna. this region encompassed the 1.0-kilobase pair woolly monkey cell-derived insertion sequence, v-sis, and flanking simian sarcoma-associated viral (ssav) sequences. a 675-nucleotide-long open reading frame commenced 19 nucleotides within the ssav sequences to the left of the v-sis helper viral junction and terminated within v-sis itself. possible promoter and acceptor sp ... | 1982 | 6285340 |
| chromosomal mapping of the simian sarcoma virus onc gene analogue in human cells. | the primate cell-derived transforming gene (v-sis) of simian sarcoma virus (ssv) is represented as a single copy marker within cellular dnas of mammalian species including human. the human analogue of v-sis can be distinguished from its rodent counterparts by southern blotting analysis of ecori-restricted dnas. by testing for the presence of the human v-sis-related fragment, c-sis (human), in somatic cell hybrids possessing varying numbers of human chromosome, as well as in segregants of such hy ... | 1982 | 6289313 |
| in vivo identification of the transforming gene product of simian sarcoma virus. | simian sarcoma virus (ssv) deletion mutants were constructed from a molecular clone containing the entire infectious provirus. transfection analysis of these mutants localized the ssv transforming gene to a small region of the viral genome encompassing its cell-derived sequence (v-sis). antiserum to a peptide synthesized on the basis of the predicted amino acid sequence of the ssv transforming gene detected a 28,000-dalton protein that was specifically expressed in ssv transformed cells and that ... | 1982 | 6293053 |
| nucleotide sequence of the simian sarcoma virus genome: demonstration that its acquired cellular sequences encode the transforming gene product p28sis. | the complete nucleotide sequence of the proviral genome of simian sarcoma virus (ssv), an acute transforming retrovirus of primate origin, has been determined. like other transforming viruses, ssv contains sequences derived from its helper virus, simian sarcoma-associated virus (ssav), and a cell-derived (v-sis) insertion sequence. by comparison with the sequence of moloney murine leukemia virus, it was possible to precisely localize and define sequences contributed by ssav during the generation ... | 1983 | 6298772 |
| complementary dna copies of leukemia and sarcoma virus rna contain sequences of deoxycytidylate and deoxyguanylate. | single-stranded complementary dna (cdna) of the rna of gazdar murine sarcoma virus, gz-msv/mulv; moloney murine leukemia virus, m-mulv; mouse mammary tumor virus, mmtv; and simian sarcoma virus, ssv-1, were synthesized in endogenous reverse transcriptase reaction. gz-msv/mulv cdna was also synthesized in exogenous in vitro reverse transcriptase reactions. in the endogenous reaction, 30-35s, or 6.0- to 7.9-kilobase-length cdna transcripts were synthesized in high yield. in comparison, transcripts ... | 1981 | 6299564 |
| the effect of hexadimethrine bromide (polybrene) on the infection of the primate retroviruses ssv 1/ssav 1 and baev. | polybrene was shown to enhance the adsorption of simian sarcoma virus-simian sarcoma associated virus complex (ssv-1/ssav-1) and baboon endogenous virus (baev) onto cells in culture. a 16- to 18-fold increased adsorption of both viruses occurred at 8 micrograms/ml polybrene within one hour after infection. the polybrene mediated adsorption was found to be inhibited by the addition of tri-sodium citrate to the culture medium, suggesting the involvement of electrostatic forces. this contention was ... | 1983 | 6301409 |
| the parodi-irgens feline sarcoma virus and simian sarcoma virus have homologous oncogenes, but in different contexts of the viral genomes. | we have identified the oncogene and the putative transforming protein of the parodi-irgens feline sarcoma virus (pi-fesv). the pi-fesv is defective and needs a helper virus for its replication. the v-onc sequences in the pi-fesv were found to be related to the v-sis sequences of the simian sarcoma virus (ssv). pi-fesv nonproducer cells express two viral rnas, a 6.8-and a 3.3-kilobase rna. the 6.8-kilobase rna contains gag, sis, and env sequences but lacks the pol gene. the 3.3-kilobase rna, on t ... | 1983 | 6302323 |
| platelet-derived growth factor is structurally related to the putative transforming protein p28sis of simian sarcoma virus. | a partial amino acid sequence of human platelet-derived growth factor, the major mitogen in serum for cells of mesenchymal origin, has been determined. a region of 104 contiguous amino acids shows virtual identity with the predicted sequence of p28sis, the putative transforming protein of simian sarcoma virus (ssv). this similarity suggests a mechanism for transformation by ssv and other agents, involving expression of growth factors. | 1983 | 6306471 |
| expression of a platelet-derived growth factor-like protein in simian sarcoma virus transformed cells. | the near identity of the partial amino acid sequence of human platelet-derived growth factor (pdgf) and that predicted for p28sis, the putative transforming protein of the simian sarcoma virus (ssv), suggests expression of a growth factor activity may be central for transformation by ssv. it is now reported that ssv-transformed cells but not control cells contain a growth factor activity that is identical to pdgf in immunoassay, in mitogenic dose response, and in specific mitogenic activity. the ... | 1983 | 6310754 |
| structural and immunological similarities between simian sarcoma virus gene product(s) and human platelet-derived growth factor. | the predicted amino acid sequence of the simian sarcoma virus (ssv) transforming gene product, p28sis, closely corresponds to that of human platelet-derived growth factor (pdgf). we demonstrate that p28sis rapidly undergoes a series of discrete processing steps including dimer formation and proteolytic digestion to yield molecules structurally and immunologically resembling biologically active pdgf. | 1983 | 6312326 |
| human-proto-oncogene nucleotide sequences corresponding to the transforming region of simian sarcoma virus. | the nucleotide sequences of the six regions within the normal human cellular locus (c-sis) that correspond to the entire transforming region of the simian sarcoma virus (ssv) genome (v-sis) were determined. the regions are bounded by acceptor and donor splice sites and, except for region 6, resemble exons. region 6 lacks a 3' donor splice site and terminates -5 base pairs from the 3' v-sis-helper-viral junction. this is consistent with a model proposing that ssv was generated by recombination be ... | 1984 | 6318322 |
| expression of the pdgf-related transforming protein of simian sarcoma virus in e. coli. | the transforming gene of simian sarcoma virus (ssv), an acute transforming retrovirus, and human platelet-derived growth factor (pdgf), a potent mitogen for connective tissue cells, appear to have arisen from the same or very closely related cellular genes. in an effort to obtain sufficient quantities of the ssv transforming gene product for the detailed analysis of its structural and biologic properties, we placed the v-sis gene under the control of strong phage transcriptional and translationa ... | 1984 | 6319011 |
| simian sarcoma virus--transformed cells secrete a mitogen identical to platelet-derived growth factor. | normal rat kidney (nrk) cells transformed by simian sarcoma virus (ssv) release into the culture medium a biologically active mitogen with properties identical to those of human platelet-derived growth factor (pdgf). like pdgf, the growth factor derived from ssv-nrk cells was shown to be stable to heat and sensitive to reducing agents. it was capable of inhibiting binding of labeled pdgf to the receptor on human fibroblasts. it also stimulated the phosphorylation of the same membrane protein (18 ... | 1984 | 6328659 |
| virus-specific phosphoproteins in simian sarcoma virus-transformed primate cells. | cells transformed by simian sarcoma virus (ssv) express a 115000-dalton protein ( p115 ) that is precipitated by a goat antiserum to disrupted ssv/ssav-infected and transformed cells but not by antibodies directed against the viral gag protein, p30, or envelope proteins. the protein is detected in productively as well as in nonproductively infected, transformed cells. it is not present in untransformed cells infected with helper virus (ssav). the protein can be phosphorylated in vivo and in vitr ... | 1982 | 6329721 |
| the c-sis gene encodes a precursor of the b chain of platelet-derived growth factor. | the relationship between platelet-derived growth factor (pdgf) and the proto-oncogene c-sis has been determined by amino acid sequence analysis of pdgf and nucleotide sequence analysis of c-sis genomic clones. the nucleotide sequences of five regions of the human c-sis gene which are homologous to sequences of the transforming region (v-sis) of simian sarcoma virus (ssv) were determined. by alignment of the c-sis and v-sis nucleotide sequences the predicted amino acid sequence of a polypeptide h ... | 1984 | 6329745 |
| nucleotide sequence of the large terminal repeat of two different strains of gibbon ape leukemia virus. | gibbon ape leukemia virus, seato strain (galv-seato), a virus that induces myeloid leukemia in gibbon apes, and galv, san francisco strain (galv-sf), a virus associated etiologically with lymphocytic leukemia in gibbon apes, have been molecularly cloned. the complete nucleotide sequence of the large terminal repeats (ltrs) of both viruses are reported and compared to the previously published nucleotide sequence of the ltr of another member of the same virus group, the simian sarcoma virus (ssv). ... | 1984 | 6474832 |
| natural antibodies to the human t cell lymphoma virus in patients with cutaneous t cell lymphomas. | sera from patients with cutaneous t cell lymphoma and leukemia were screened for the presence of natural antibody to the human t cell lymphoma (leukemia) virus, htlvcr, using a solid-phase radioimmunoassay. sera from two patients, including patient cr, from whose cultured t lymphoblastic cell line (hut102), the retrovirus htlvcr was isolated, reacted specifically with proteins of htlvcr. serum from patient cr also reacted specifically with proteins of htlvmb, an independent but highly related re ... | 1981 | 6973601 |
| platelet derived growth factor/tyrosine kinase receptor mediated proliferation. | pdgf heterodimer of a and b chains, a complete mitogen for 3t3 mouse fibroblasts, exemplifies those growth factors interacting with membrane associated tyrosine kinase receptors. its binding to the pdgf-receptors results in receptor dimerization and subsequent activation of tyrosine kinase activity in the cytoplasmic protein domain, autophosphorylation of the receptor being the first event in the transduction cascade. before the ligand-receptor complex is internalized and degraded, receptor stim ... | 1993 | 8220110 |
| complete nucleotide sequence of sugarcane streak monogeminivirus. | the complete nucleotide sequence of the genome of the monogeminivirus sugarcane streak virus (ssv) was determined from cloned replicative form dna. the genome is contained in one dna circle of 2,758 nucleotides, and has four open reading frames with the potential to encode proteins of mw > 10 kda: two in the viral (+) sense and two in the complementary (-) sense. each open reading frame has a counterpart among the open reading frames reported for other monogeminiviruses. a potential binding site ... | 1993 | 8352656 |
| ssv1-encoded site-specific recombination system in sulfolobus shibatae. | we present evidence for the existence of a conservative site-specific recombination system in archaea by demonstrating integrative recombination of sulfolobus shibatae virus ssv1 dna with the host chromosome, catalysed by the ssv1-encoded integrase in vitro. the putative int gene of ssv1 was expressed in escherichia coli yielding a protein of about 39 kda. this protein alone efficiently recombined linear dna substrates containing chromosomal (atta) and viral (attp) attachment sites; recombinatio ... | 1993 | 8483447 |
| platelet-derived growth factor in human glioma. | platelet-derived growth factor (pdgf) is a 30 kda protein consisting of disulfide-bonded dimers of a- and b-chains. pdgf receptors are of two types, alpha- and beta-receptors, which are members of the protein-tyrosine kinase family of receptors. the receptors are activated by ligand-induced dimerization, whereby the receptors become phosphorylated on tyrosine residues. these form attachment sites for signalling molecules, which inter alia activate the ras.raf pathway. pdgf has important function ... | 1995 | 8586462 |