| viral superinfection in cells carrying an arenavirus and/or a togavirus. | four lines of the same l-cell clone were transferred 60 times in parallel: uninfected cells, a line carrying lymphocytic choriomeningitis virus (lcmv), another one carrying tick-borne encephalitis virus (tev) and one carrying both viruses. in double persistency, lcm and tev were suppressed and stimulated, respectively. cell multiplication rates were comparable in all four lines. single lcmv persistence caused marked resistance of l cells to superinfecting viruses from various taxonomic groups, b ... | 1978 | 35946 |
| selective resistance to togaviral superinfection in mice with tolerant lymphocytic choriomeningitis virus infection. | mice infected neonatally with lymphocytic choriomeningitis virus (lcmv) developed partial and complete resitance to cerebral superinfection with tick-borne encephalitis virus (tev) in 10 and 20 days after birth, respectively. this resistance lasted at least till the age of 40 days. lcmv tolerant mice neither succumbed to tev infection, nor circulated tev in their blood. moderate, gradually decreasing tev titres were detected in the brains and tev-induced brain interferon was lower than in contro ... | 1979 | 42297 |
| experimental mixed infection with two tick-borne viruses and interferon-mediated interference. | tick-borne encephalitis virus (tev), a flavivirus, and lipovník virus (lv), a member of the kemerovo group and complex and possible member of the rioviridae, were used to infect chick embryo cell (cec) cultures. lv reproduction was inhibited by preinfection with tev, mainly in aged cultures. in young cec cultures, tev production was stimulated slightly and interferon was sometimes depressed by this superinfection; on the contrary, in aged cultures the superinfecting lv stimulated interferon also ... | 1975 | 235191 |
| the rna of tobacco etch virus contains poly(a). | | 1979 | 425327 |
| protection against detrimental effects of potyvirus infection in transgenic tobacco plants expressing the papaya ringspot virus coat protein gene. | we obtained transgenic tobacco plants expressing the papaya ringspot virus (prv) coat protein (cp) gene by transformation via agrobacterium tumefaciens. expression was effectively monitored by enzyme-linked immunosorbent assays (elisa) of crude tissue extracts. subcloned plants derived from eight original ro transformants were inoculated with potyviruses: tobacco etch (tev), potato virus y (pvy), and pepper mottle (pemv). plants that accumulated detectable levels of the prv cp showed significant ... | 1991 | 1367635 |
| a nuclear localization signal and the c-terminal omega sequence in the agrobacterium tumefaciens vird2 endonuclease are important for tumor formation. | the t-dna portion of the agrobacterium tumefaciens tumor-inducing (ti) plasmid integrates into plant nuclear dna. direct repeats define the t-dna ends; transfer begins when the vird2 endonuclease produces a site-specific nick in the right-hand border repeat and attaches to the 5' end of the nicked strand. subsequent events generate linear single-stranded vird2-bound dna molecules that include the entire t-dna (t-strands). vird2 protein contains a nuclear localization signal (nls) near the c term ... | 1992 | 1465407 |
| coat protein properties suggest that azuki bean mosaic virus, blackeye cowpea mosaic virus, peanut stripe virus, and three isolates from soybean are all strains of the same potyvirus. | the interrelationship of a number of potyviruses infecting legumes has been investigated by comparing molecular properties of their coat proteins. comparison of the coat proteins by the techniques of amino acid analysis and page was inadequate to distinguish strains from distinct potyviruses. however, high-performance liquid chromatographic peptide profiles of tryptic digests of coat proteins of these legume-infecting potyviruses enabled such assignments to be made. these data indicate that amin ... | 1992 | 1500273 |
| nucleotide sequence of the 3'-terminal region of potato virus a rna. | the sequence of the 3'-terminal region of the genome of the potato virus a (pva) was obtained from two independent cdna clones. this sequence is 1383 nucleotides long and contains an open reading frame of 1178 nucleotides, ending with the translation termination codon taa and followed by untranslated region of 205 nucleotides. since the n-terminal amino acid of the coat protein of pva was blocked, the position of the putative coat protein cleavage site has been deduced by searching for consensus ... | 1992 | 1604933 |
| cleavage profiles of tobacco etch virus (tev)-derived substrates mediated by precursor and processed forms of the tev nia proteinase. | nucleotide sequences coding for proteins containing the tobacco etch virus (tev) nia proteinase were generated by polymerase chain reaction amplification and/or site-directed mutagenesis. these coding regions contained sequences for the proteinase alone or as part of higher mr precursors. following transcription and translation of these sequences in a cell-free system, the various polyproteins, all containing an active small nuclear inclusion protein (nia) proteinase, were used to process a tev ... | 1992 | 1730935 |
| the complete nucleotide sequence of pea seed-borne mosaic virus rna. | the complete nucleotide sequence of the rna genome of pea seed-borne mosaic virus (psbmv) was determined from cloned cdna and by direct sequencing of viral rna. the psbmv genomic sequence was determined to be 9924 nucleotides in length excluding the poly(a) tract. the rna contained an open reading frame (orf) of 9618 nucleotides with the potential to encode a polyprotein with a calculated mr of 364000 (364k). the orf was flanked by a 5' untranslated leader sequence of 143 nucleotides and a 3' un ... | 1991 | 1940858 |
| proteolytic activity of plum pox virus-tobacco etch virus chimeric nia proteases. | plasmids encoding chimeric nia-type proteases made of sequences from the potyviruses plum pox virus (ppv) and tobacco etch virus (tev) have been constructed. their proteolytic activity on the large nuclear inclusion protein (nib)-capsid protein (cp) junction of each virus was assayed in escherichia coli cells. the amino half of the protease seemed to be involved neither in the enzymatic catalysis nor in substrate recognition. in spite of the large homology among the ppv and tev nia-type protease ... | 1991 | 2015911 |
| the establishment of rat hybridoma cell lines secreting mcab against strains of potato virus y and analysis of its stability. | the rat splenocytes immunized with potato virus y (pvyn) and ratmyeloma (ir983) were fused by peg (m. w.1450). three kinds of stable hybridoma cell lines secreting specific monoclonal antibodies (mcabs) were derived. one kind of the cell lines producing mcabs reacts to pvyn specifically. another reacts to pvyo specifically. the third one reacts to both of the two strains. tested by the methods of sandwich-elisa and indirect-elisa, all kinds of mcabs did not react to seven plant viruses: tobacco ... | 1990 | 2104212 |
| determination of polyprotein processing sites by amino terminal sequencing of nonstructural proteins encoded by plum pox potyvirus. | nonstructural proteins of plum pox potyvirus were partially purified following a procedure described for the isolation of tobacco etch virus nuclear inclusion proteins. plum pox virus proteins with electrophoretic mobilities corresponding to 49, 59 and 68 kda reacted with antibodies against the 49 kda and 54 kda components of the nuclear inclusions and the 70 kda component of the cylindrical inclusions of tobacco etch virus, respectively. further purification by size exclusion high performance l ... | 1990 | 2138835 |
| a novel human immunodeficiency virus type 1 protein, tev, shares sequences with tat, env, and rev proteins. | we have characterized a novel 28-kilodalton protein, p28tev, detected in human immunodeficiency virus type 1-infected cells. tev is recognized by both tat and rev monospecific antibodies. tev is initiated at the tat aug and contains the first exon of tat at its amino terminus, a small portion of env in the middle, and the second exon of rev at its carboxy terminus. a cdna clone producing tev was cloned and expressed in human cells. sequence analysis revealed that the tev mrna is generated by spl ... | 1990 | 2186172 |
| the vpg of tobacco etch virus rna is the 49-kda proteinase or the n-terminal 24-kda part of the proteinase. | preparations of tobacco etch virus (tev) rna which were purified by sucrose gradient centrifugation, digested with rnase, and analyzed by sds-polyacrylamide gel electrophoresis contained proteins of 49, 32, and 24 kda. the 49- and 24-kda proteins reacted with polyclonal antiserum to the tev 49-kda proteinase while the 32-kda protein reacted with anti-tev serum. further purification of the rna by centrifugation through cscl removed the coat protein (32 kda), but not the 49- and 24-kda proteins. t ... | 1990 | 2202147 |
| expression of potyviral polyproteins in transgenic plants reveals three proteolytic activities required for complete processing. | all proteins encoded by the plant potyvirus, tobacco etch virus (tev), arise by proteolytic processing of a single polyprotein. two virus-encoded proteinases (nia and hc-pro) that catalyze most of the proteolytic events have been characterized previously. the two proteins that are derived from the n-terminal 87 kd region of the viral polyprotein are a 35 kd protein and hc-pro (52 kd). it is demonstrated in this study that a third proteolytic activity is required to process the junction between t ... | 1990 | 2184028 |
| nuclear transport of plant potyviral proteins. | we have used immunoblotting, immunocytochemical, and gene fusion methods to examine the differential subcellular partitioning of tobacco etch potyvirus proteins that are potentially associated with rna replication. from the earliest timepoints at which viral proteins could be detected, proteins nla (49-kilodalton proteinase) and nlb (58-kilodalton polymerase) were localized primarily in the nucleus, whereas the 71-kilodalton cylindrical inclusion protein was identified in the cytoplasm. the nla ... | 1990 | 2136629 |
| characterization of the catalytic residues of the tobacco etch virus 49-kda proteinase. | the 49-kda proteinase of tobacco etch virus (tev) cleaves the polyprotein derived from the tev genomic rna at five locations. molecular genetic and biochemical analyses of the 49-kda tev proteinase were performed to test its homology to the cellular trypsin-like serine proteases. a cdna fragment, containing the tev 49-kda proteinase gene and flanking sequences, was expressed in a cell-free transcription/translation system and resulted in the formation of a polyprotein precursor that underwent ra ... | 1989 | 2475971 |
| direct selection for sequences encoding proteases of known specificity. | we have developed a simple genetic selection that could be used to isolate eukaryotic cdnas encoding proteases that cleave within a defined amino acid sequence. the selection was developed by using the transcription factor gal4 from saccharomyces cerevisiae as a selectable marker, a cloned protease from tobacco etch virus (tev), and an 18-amino acid tev protease target sequence. in yeast, tev protease cleaves its target even when the target is fused to internal regions of the gal4 protein. this ... | 1991 | 2052595 |
| artificial cleavage site recognized by plum pox potyvirus protease in escherichia coli. | a synthetic plum pox virus (ppv) nib-cp cleavage site was recognized by a ppv protease in an in vivo escherichia coli expression system. the presence of the natural nib-cp cleavage site did not affect processing at the artificial one. however, although both the proteases and the cleavage sites of ppv and tobacco etch virus show high sequence homology, a similar cassette from the tobacco etch virus nib-cp junction was not efficiently recognized by the ppv protease. | 1989 | 2657098 |
| substrate recognition by the nia proteinase of two potyviruses involves multiple domains: characterization using genetically engineered hybrid proteinase molecules. | the proteolytic activity associated with the small nuclear inclusion protein (nia proteinase) of tobacco etch virus (tev), a potyvirus, catalyzes several cleavages at sites within the polyprotein derived from the tev rna genome. the homologous proteinase of tobacco vein mottling virus (tvmv), a closely related potyvirus, cleaves at similar, yet distinct, recognition sites. we examined these proteinases, in a cell-free cleavage system, in an attempt to define the biochemical basis of substrate sp ... | 1991 | 2024462 |
| molecular cloning, sequencing and expression in escherichia coli of the bean yellow mosaic virus coat protein gene. | the sequence of 1015 nucleotides from the 3' poly(a) tract of the potyvirus bean yellow mosaic virus (bymv) rna has been determined from two cdna clones. this sequence contained a single long open reading frame (orf) starting upstream of the cloned region. the orf was expressed as a fusion protein in escherichia coli, and the product was detected by antibodies specific for the coat protein of bymv. the predicted length of the coat protein gene was 822 nucleotides, corresponding to a 273 amino ac ... | 1989 | 2671258 |
| a temporal study of the expression of the capsid, cytoplasmic inclusion and nuclear inclusion proteins of tobacco etch potyvirus in infected plants. | young leaves of tobacco, systemically infected by tobacco etch potyvirus (tev), were examined for the presence and distribution of four virus encoded proteins [capsid, cytoplasmic inclusion (ci) and two nuclear inclusion (ni) proteins] at various time periods after inoculation of expanded leaves of the plants. the analyses were carried out by elisa and by immunogold electron microscopy of thin sections of the leaves. all four proteins were detected simultaneously in the systemic leaves for the f ... | 1991 | 2005427 |
| in vitro cleavage at or near the n-terminus of the helper component protein in the tobacco vein mottling virus polyprotein. | translation of tobacco vein mottling virus (tvmv) rna in a wheat germ system resulted in two products that were not observed in a rabbit reticulocyte system. one of these was the n-terminal protein, based on its being the most abundant product and its migration on sds-page at about 34 kda. the second product was similar or identical to helper component (hc) isolated from tvmv-infected plants, based on co-migration with hc on sds-page and immunoprecipitation with anti-hc antibodies. the n-terminu ... | 1991 | 1962446 |
| post-translational processing of the tobacco etch virus 49-kda small nuclear inclusion polyprotein: identification of an internal cleavage site and delimitation of vpg and proteinase domains. | the 49,000-dalton (49-kda) small nuclear inclusion (ni) protein of tobacco etch virus (tev) has two distinct functions associated with it. an n-terminal segment is covalently attached to the genomic length rna and likely involved in rna replication, while the c-terminal half is associated with a proteolytic activity critical for genome expression. the junction delineating these two proteins has not been identified. we have analyzed naturally occurring cleavage products of tev ni proteins and hav ... | 1991 | 1853555 |
| characterization of the potyviral hc-pro autoproteolytic cleavage site. | the helper component-proteinase (hc-pro) encoded by potyviruses functions to cleave the viral polyprotein by an autoproteolytic mechanism at the hc-pro c-terminus. this protein belongs to a group of viral cysteine-type proteinases and has been shown previously to catalyze proteolysis between a gly-gly dipeptide. the amino acid sequence requirements surrounding the hc-pro c-terminal cleavage site of the tobacco etch virus polyprotein have been investigated using site-directed mutagenesis and in v ... | 1992 | 1736533 |
| nucleotide sequence of the 3'-terminal region of potato virus yn rna. | the sequence of the 3'-terminal 1611 nucleotides of the genome of the tobacco veinal necrosis strain of potato virus y (pvyn) was determined. the sequence revealed an open reading frame of 1285 nucleotides, of which the start was not identified, and an untranslated region of 316 nucleotides upstream of a poly(a) tract. comparison of the open reading frame with the amino-terminal sequence of the viral coat protein enabled mapping of the start of the coat protein at amino acid -267, and indicated ... | 1989 | 2732687 |
| the complete nucleotide sequence of plum pox virus rna. | the complete nucleotide sequence of the rna of an aphid non-transmissible plum pox virus (ppv-nat) isolate has been determined from five overlapping cdna clones. cdna prepared by primer extension was used to determine the 5' terminus. the assembled rna is 9741 nucleotides in length, excluding a 3' terminal poly(a) sequence. one large open reading frame starts at nucleotide positions 36 to 38 and is terminated with an uag codon at positions 9522 to 9524. the putative start codon is located at pos ... | 1989 | 2732699 |
| nucleotide sequence of potato virus y (n strain) genomic rna. | the complete nucleotide sequence of the genomic rna of the potyvirus potato virus y strain n (pvyn) was obtained from cloned cdnas. this sequence is 9704 nucleotides long and can encode a polyprotein of 3063 amino acids. the positions of the cleavage sites at the n terminus of the capsid and cytoplasmic inclusion proteins have been determined. other putative protein cleavage sites have been deduced by searching for consensus sequences and by analogy with the polyprotein of the tobacco vein mottl ... | 1989 | 2732709 |
| the complete nucleotide sequence of plum pox potyvirus rna. | the complete nucleotide sequence of the plum pox virus (ppv) rna genome has been determined. the rna sequence is 9786 nucleotides in length, excluding the 3'-terminal poly(a) tail. an aug triplet at position 147-149 was assigned as the initiation codon for the translation of the genome size viral polyprotein which would consist of 3140 amino acid residues. the nucleotide sequence of the non-coding regions and the predicted amino acid sequence of the polyprotein of ppv were compared with those pr ... | 1989 | 2773595 |
| the genome-linked protein and 5' end rna sequence of plum pox potyvirus. | the infectivity of plum pox potyvirus (ppv) rna was decreased by treatment with proteases. ribonuclease digestion of iodinated ppv rna yielded material which had an electrophoretic mobility corresponding to mr 22,000. this protein presumably corresponds to the protease-sensitive structure needed for infectivity. a protein-linked rnase t1-resistant oligonucleotide, 38 nucleotides long, was sequenced and shown to correspond to the 5' terminus of the rna by sequence comparison to the rnas of two ot ... | 1989 | 2794981 |
| untranslatable transcripts of the tobacco etch virus coat protein gene sequence can interfere with tobacco etch virus replication in transgenic plants and protoplasts. | transgenic tobacco plants which express untranslatable sense or antisense forms of the tobacco etch virus potyvirus (tev) coat protein (cp) gene sequence have been generated. one of seven transgenic plant lines expressing a cp gene antisense transcript showed an attenuation of symptoms when inoculated with tev. three of ten transgenic plant lines expressing untranslatable sense transcripts did not develop symptoms when inoculated with tev. these lines were resistant to either aphid or mechanical ... | 1992 | 1641986 |
| coat protein of potyviruses. 5. symptomatology, serology, and coat protein sequences of three strains of passionfruit woodiness virus. | three strains of passionfruit woodiness virus, tip blight (pwv-tb), severe (pwv-s) and mild (pwv-m), were compared on the basis of their biological, serological and coat protein structural properties. each of the strains could be distinguished on the basis of their reactions on selected test plant species but no differences were observed in the serological properties of the three pwv strains. molecular weight estimates on sds-page suggest the pwv coat protein contains 275 amino acid residues and ... | 1988 | 3202695 |
| autocatalytic activity of the tobacco etch virus nia proteinase in viral and foreign protein sequences. | the small nuclear inclusion (nia) protein of the tobacco etch virus (tev) is synthesized initially as part of a genome-derived high m(r) precursor. the nia protein releases itself from this genome-derived precursor by self-cleavage, or an autocatalytic processing event. cleavage between specific glutamine-glycine dipeptides at the n and c termini generates the 430 amino acid or 49,000 m(r) (49k) nia protein. the requirements of this autocatalytic release, or cis cleavage, were examined by constr ... | 1992 | 1634873 |
| mutational analysis of tobacco etch virus polyprotein processing: cis and trans proteolytic activities of polyproteins containing the 49-kilodalton proteinase. | the genome of tobacco etch virus contains a single open reading frame with the potential to encode a 346-kilodalton (kda) polyprotein. the large polyprotein is cleaved at several positions by a tobacco etch virus genome-encoded, 49-kda proteinase. the locations of the 49-kda proteinase-mediated cleavage sites flanking the 71-kda cytoplasmic pinwheel inclusion protein, 6-kda protein, 49-kda proteinase, and 58-kda putative polymerase have been determined by using cell-free expression, proteolytic ... | 1988 | 3286889 |
| mapping of the tobacco vein mottling virus vpg cistron. | the location of the cistron encoding the genome-linked protein (vpg) in the potyvirus tobacco vein mottling virus (tvmv) was investigated. precipitation of 125i-labeled vpg with anti-tobacco etch virus 49k nuclear inclusion protein antiserum (which reacts with the nia nuclear inclusion protein of tvmv) indicated that the tvmv vpg is immunologically related to nia. lysyl residues were found to be present at positions 2, 11, and 16 of the amino-terminal region of the vpg. a search of the tvmv poly ... | 1988 | 3354210 |
| pathogen-derived resistance to a potyvirus: immune and resistant phenotypes in transgenic tobacco expressing altered forms of a potyvirus coat protein nucleotide sequence. | transgenic nicotiana tabacum 'burley 49' plants containing one of six different forms of the tobacco etch virus (tev) coat protein (cp) nucleotide sequence have been generated. in whole plant studies, r1 and r2 progeny were inoculated mechanically with tev, and the appearance and severity of symptoms were recorded. symptom phenotype was altered, ranging from near wild type susceptibility to apparent immunity. protoplasts derived from wild type and transgenic burley 49 plant lines were transfecte ... | 1992 | 1617197 |
| the 5' untranslated region from pea seedborne mosaic potyvirus rna as a translational enhancer in pea and tobacco protoplasts. | we have exploited the transient expression of foreign genes introduced into plant protoplasts to investigate the effect of the pea seedborne mosaic potyvirus (psbmv) 5' untranslated region (5'utr) on the level of gene expression in pea and tobacco protoplasts. the plant viral 5'utrs were found to increase translation significantly in comparison to a plasmid containing no 5'utr of viral origin. the enhancement effect of the 5'utrs of psbmv and tobacco etch potyvirus (tev) was found to be similar ... | 1992 | 1607015 |
| association of tobacco etch virus related rna with chloroplasts in extracts of infected plants. | the rna in various subcellular fractions of tobacco etch virus (tev) infected tissue was analyzed for the presence of complementary viral rna, and double-stranded viral rna by hybridization with 32p-labeled viral rna or cdna probes. although viral rna was detected in several cellular fractions, the complementary rna of full-length size was found exclusively associated with fractions containing chloroplasts. treatment of rnas with rnase before hybridization suggested that the virus-related comple ... | 1986 | 3952987 |
| partial purification of inclusions induced by tobacco etch virus and potato virus y. | | 1971 | 4107552 |
| partial purification and some properties of tobacco etch virus induced intranuclear inclusions. | | 1974 | 4213287 |
| the complete nucleotide sequence of rna 1 of a german isolate of barley yellow mosaic virus and its comparison with a japanese isolate. | the nucleotide sequence of rna 1 of a german isolate of barley yellow mosaic virus has been determined and compared with a japanese isolate of the same virus. the sequence identity is 93.6% at the nucleotide level and 96% at the amino acid level. similar values have been found for the polyproteins of the rna 2 of both isolates (95%). both isolates show an rna 1-encoded protein arrangement similar to that of potyviruses such as tobacco etch virus. in contrast, the polyproteins of the small rnas ( ... | 1992 | 1588327 |
| tobacco etch virus cylindrical inclusions: antigenically unrelated to the causal virus. | | 1969 | 4891219 |
| some properties of tobacco etch virus and its alkaline degradation products. | | 1966 | 4956897 |
| some of the chemical properties of the tobacco etch virus and its protein and nucleic acid components. | | 1970 | 5411195 |
| electron microscopy of subtilisin-treated tobacco etch virus nuclear and cytoplasmic inclusions. | | 1968 | 5677120 |
| effects of antisense oligodeoxynucleotide hybridization on in vitro translation of potato virus y rna. | potato virus y (pvy), a potyvirus, has an rna genome containing 9704 nucleotides of which 185 belong to the 5' nontranslated region (ntr). contrary to most eukaryotic mrnas that have a cap structure, the potyvirus rna has a genome-linked protein (vpg). in order to understand the mechanisms of pvy rna translation initiation, hybrid-arrest translation was used to localize sequences involved in binding of proteins and/or ribosomes. the 5' ntr was fused to the beta-glucuronidase (gus) reporter gene. ... | 1992 | 1549909 |
| physiology of tobacco etch virus-induced wilt of tabasco peppers. | | 1967 | 6017400 |
| electron microscopy of host cells infected with tobacco etch virus. iv. tritiated uridine and leucine uptake of intracellular virus and intranuclear crystalline inclusions. | | 1967 | 6039962 |
| electron microscopy of mixed infections with two plant viruses. i. intracellular interactions between tobacco mosaic virus and tobacco etch virus. | | 1967 | 6039964 |
| mutational analysis of the tobacco etch potyviral 35-kda proteinase: identification of essential residues and requirements for autoproteolysis. | the tobacco etch potyvirus (tev) polyprotein is processed by three virus-encoded proteinases, termed nla, hc-pro, and the 35-kda proteinase. the 35-kda proteinase is derived from the amino-terminal region of the polyprotein. analysis of polyproteins containing beta-glucuronidase fused to the expected carboxy terminus of the 35-kda proteinase confirmed the previously identified tyr304-ser305 dipeptide as the cleavage site between the 35-kda proteinase and hc-pro. the 35-kda proteinase of tev was ... | 1992 | 1529535 |
| cross-reactive potential of monoclonal antibodies raised against proteolysed tobacco etch virus. | monoclonal antibodies (mab) capable of reacting with different potyviruses were obtained by immunizing mice with proteolysed tobacco etch virus. the mab were not equally effective in all elisa formats and some were specific for different conformational states of the viral coat protein. the mab also detected antigenic differences between purified virus particles and viral antigen in infected plant sap. in an elisa format using antigen-coated plates, 5 different potyviruses (out of 7 viruses teste ... | 1992 | 1518965 |
| regulation of nuclear transport of a plant potyvirus protein by autoproteolysis. | the nia proteinase encoded by tobacco etch potyvirus catalyzes six processing events, three of which occur by an autoproteolytic mechanism. autoproteolysis is necessary to cleave the boundaries of both nia and the 6-kda protein, which is located adjacent to the n terminus of nia in the viral polyprotein. as a consequence, nia may exist in a free form or in a transient polyprotein form containing the 6-kda protein. while the majority of nia molecules localize to the nuclei of infected cells, a fr ... | 1992 | 1501298 |
| is pepper mottle virus a strain of potato virus y? | on the basis of serological properties and host plant reactions pepper mottle virus (pepmov) has been classified as a potyvirus related to, but distinct from, other pepper-infecting potyviruses, potato virus y (pvy) and tobacco etch virus (tev). recent amino acid and nucleotide sequence data show that pepmov is more closely related to pvy than previously assumed. pepmov shows a high degree of homology to various pvy strains in both the coat protein and the 3' non-translated sequences, while unre ... | 1992 | 1450759 |
| biological variants of tobacco etch virus that induce morphologically distinct nuclear inclusions. | the presence of distinctive nuclear inclusions has been used for many years as a diagnostic character for tobacco etch virus (tev). cytological examinations of isolates of tev in both weeds and solanaceous crops from areas widely separated geographically have demonstrated the presence of a variety of nuclear inclusions that vary considerably in form. such inclusions can, in many cases, be related to differences in symptom expression. it is suggested that distinctive nuclear inclusions may be use ... | 1992 | 1450742 |
| tagging of plant potyvirus replication and movement by insertion of beta-glucuronidase into the viral polyprotein. | infectious rna transcripts were generated from full-length cdna clones of the tobacco etch potyvirus genome containing an insertion of the bacterial beta-glucuronidase (gus) gene between the polyprotein-coding sequences for the n-terminal 35-kda proteinase and the helper component-proteinase. the recombinant virus was able to spread systemically in plants and accumulated to a level comparable with wild-type tobacco etch potyvirus. proteolytic processing mediated by the 35-kda proteinase and help ... | 1992 | 1438210 |
| expression and purification of a recombinant tobacco etch virus nia proteinase: biochemical analyses of the full-length and a naturally occurring truncated proteinase form. | the tobacco etch virus 27-kda nuclear inclusion a (nia) proteinase was expressed in escherichia coli as a recombinant fusion protein containing a seven-histidine tag at the amino-terminus. catalytically active and inactive (by virtue of a single amino acid change) forms of the proteinase were purified to homogeneity in a two-column chromatographic procedure. the active form of the proteinase was slowly converted to a lower molecular weight form, while the inactive form was not. this conversion w ... | 1995 | 7793070 |
| suppression of an arenavirus by a togavirus in experimental acute double infection. | lymphocytic choriomeningitis virus (lcmv) and tick-borne encephalitis virus (tev) were inoculated in young and old chick embryo cell (cec) and in l-cell cultures at various multiplicities per cell, simultaneously or 17 hr apart. the yield of infective lcmv was inhibited in double infection, most in old cec with elevated interferon mechanisms, and least in l cells producing no interferon. in young cec, tev-induced interferon was stimulated by coinfecting lcmv; lcmv alone never has induced interfe ... | 1978 | 30264 |
| the complete nucleotide sequence of pepper mottle virus genomic rna: comparison of the encoded polyprotein with those of other sequenced potyviruses. | the complete nucleotide sequence of a pepper mottle virus isolate from california (pepmov c) has been determined from cloned viral cdnas. the pepmov c genomic rna is 9640 nucleotides excluding the poly(a) tail and contains a long open reading frame starting at nucleotide 168 and potentially encoding a polyprotein of 3068 amino acids. comparison of the pepmov c presumptive polyprotein with those of other sequenced members of the potyvirus group, including tobacco etch virus (tev), tobacco vein mo ... | 1992 | 1413501 |
| sphere-linked immunodiagnostic assay (slida): an electron microscopic method for detecting specific antibodies. | we have developed a sensitive method, sphere-linked immunodiagnostic assay, using specific antigens covalently bonded to microspheres for the detection of antibodies in serum. in this method, specific antigens, such as the capsid proteins of tobacco mosaic virus and tobacco etch virus, were independently, covalently bonded to plastic micropheres of 0.5 microns or 0.9 microns in diameter. the antigen-linked spheres were then exposed to normal serum or serum containing specific antibody, followed ... | 1990 | 2223076 |
| different sites of interaction for rev, tev, and rex proteins within the rev-responsive element of human immunodeficiency virus type 1. | we have analyzed the action of the rev and tev proteins of human immunodeficiency virus type 1 (hiv-1) and of the rex protein of human t-cell leukemia virus type i (htlv-i) on a series of rev-responsive element (rre) mutants. the minimum continuous rre region necessary and sufficient for rev function was determined to be 204 nucleotides. interestingly, this region was not sufficient for tev or rex function. these proteins require additional sequences, which may stabilize the structure of the rre ... | 1990 | 2243384 |
| mutational analysis of plum pox potyvirus polyprotein processing by the nia protease in escherichia coli. | a binary escherichia coli expression system has been used to study the pathway for proteolytic processing of the plum pox potyvirus (ppv) polyprotein. trans cleavage at the carboxyl end of the cylindrical inclusion protein occurred, although with lower efficiency than that at the large nuclear inclusion protein-capsid protein junction. no trans cleavage at the carboxyl end of the small nuclear inclusion protein (nia) was detected. the proteolytic activities at different cleavage sites of several ... | 1990 | 2273380 |
| cap-independent enhancement of translation by a plant potyvirus 5' nontranslated region. | the rna genome of tobacco etch virus (tev), a plant potyvirus, functions as an mrna for synthesis of a 346-kilodalton polyprotein that undergoes extensive proteolytic processing. the rna lacks a normal 5' cap structure at its terminus, which suggests that the mechanism of translational initiation differs from that of a normal cellular mrna. we have identified a translation-enhancing activity associated with the 144-nucleotide, 5' nontranslated region (ntr) of the tev genome. when fused to a repo ... | 1990 | 2319646 |
| a second proteinase encoded by a plant potyvirus genome. | the rna genome of tobacco etch virus (tev) encodes a large polyprotein precursor that is processed to mature proteins by virus-specific proteinases. cleavage sites located within the carboxyl-terminal two-thirds of the polyprotein are processed by a tev-encoded 49 kd proteinase, while the enzyme(s) responsible for cleaving the remaining sites has not been found. in this study, a second tev-encoded proteinase has been identified based on cell-free expression of defined rna transcripts. the bounda ... | 1989 | 2656254 |
| molecular genetic analysis of a plant virus polyprotein cleavage site: a model. | the rna genome of tobacco etch virus (tev) is expressed as a polyprotein which is co- and post-translationally processed by viral encoded proteinases. the tev 49,000 dalton (49-kda) proteinase cleaves the polyprotein at five positions each defined by the seven amino acid consensus sequence, (formula; see text) one of the cleavage sites, the 58-kda nuclear inclusion/30-kda capsid protein junction was altered by site-directed mutagenesis and the effects of these alterations on cleavage were determ ... | 1989 | 2669323 |
| molecular genetic and biochemical evidence for the involvement of the heptapeptide cleavage sequence in determining the reaction profile at two tobacco etch virus cleavage sites in cell-free assays. | potyviruses express their genetic information from a genome length rna as a single polyprotein, which is post-translationally processed by at least two different viral-encoded proteolytic activities. since regulation of the expression of individual genes is not likely to occur at the transcriptional level, we sought to determine if post-translational regulation of gene expression was possible via differential proteolytic processing. modulating the rate of cleavage at different gene product junct ... | 1989 | 2672562 |
| autocatalytic processing of the potyvirus helper component proteinase in escherichia coli and in vitro. | the virus-encoded proteins of tobacco etch virus (tev), a plant potyvirus, arise by proteolytic processing of a large polyprotein precursor. the tev genome codes for two proteinases, a 49-kilodalton proteinase and helper component proteinase (hc-pro), which cleave the polyprotein at specific sites. the only known cleavage event catalyzed by hc-pro occurs at the hc-pro carboxyl terminus. the proteolytic activity of hc-pro was analyzed by expression of the enzyme in bacterial and cell-free systems ... | 1989 | 2674480 |
| generation and characterization of monoclonal antibodies reactive with the 49-kda proteinase of tobacco etch virus. | monoclonal antibodies (mcabs) were generated against two tobacco etch virus (tev)-encoded nonstructural proteins, the 49-kilodalton (kda) proteinase and the 58-kda putative rna-dependent rna polymerase. this process was facilitated by the fact that these two tev nonstructural proteins cocrystallize in the nuclei of virus-infected cells to form nuclear inclusion (ni) bodies which can be purified readily. the anti-ni mcabs were shown by western blot analysis to be specific for either the tev 49-kd ... | 1989 | 2688299 |
| identification of essential residues in potyvirus proteinase hc-pro by site-directed mutagenesis. | two virus-encoded proteinases are responsible for proteolysis of potyvirus polyproteins. one of these, hc-pro, is a multifunctional protein that autolytically cleaves at its carboxyl-terminus (j.c. carrington et al., 1989, embo j. 8, 365-370). to identify the class of proteinase to which hc-pro belongs, tobacco etch virus (tev) hc-pro mutants containing single amino acid substitutions at serine, cysteine, aspartic acid, and histidine positions were synthesized by in vitro transcription and trans ... | 1989 | 2688301 |
| complementary dna cloning and expression of the papaya ringspot potyvirus sequences encoding capsid protein and a nuclear inclusion-like protein in escherichia coli. | three cdna clones that express viral gene products in escherichia coli jm83 were derived from a watermelon mosaic virus-1 strain of papaya ringspot virus (prsv-w). dnas complementary to portions of the viral rna were inserted into the puc8 and puc9 plasmids, and the expressed polypeptides were fusion products with the amino terminus of beta-galactosidase. clones w1-77 and w2-1 expressed fusion products with apparent molecular weights of 40,000 (40k) and 14k, respectively, which were serologicall ... | 1985 | 2998020 |
| a viral cleavage site cassette: identification of amino acid sequences required for tobacco etch virus polyprotein processing. | mature viral-encoded proteins of tobacco etch virus (tev) arise by proteolytic processing of a large precursor. the proteinase responsible for most of these cleavages is a viral-encoded 49-kda protein. all known or predicted cleavage sites in the tev polyprotein are flanked by the conserved sequence motif glu-xaa-xaa-tyr-xaa-gln-ser or gly, with the scissile bond located between the gln-ser or gly dipeptide. by using cell-free systems to manipulate and express cloned cdna sequences, a 25-amino a ... | 1988 | 3285343 |
| biochemical and mutational analysis of a plant virus polyprotein cleavage site. | the rna genome of tobacco etch virus (tev) is organized as a single translational unit coding for a 346,000 (346 kd) mol. wt (mr) polyprotein. the 346 kd mr polyprotein is cleaved by a 49 kd mr virus-encoded proteinase at five different sites between the dipeptides gln-ser or gln-gly. these cleavage sites or gene product boundaries are defined by the heptapeptide sequence...glu-xaa-xaa-tyr-xaa-gln-ser or gly.... we have used the 54 kd mr nuclear inclusion protein/30 kd mr capsid protein junction ... | 1988 | 3409865 |
| antibody-mediated activation of sindbis virus. | the biological activity of an anti-sindbis monoclonal antibody (mcab 49) has been explored. the antibody recognizes an epitope on the e2 glycoprotein of sindbis virus and, in the presence of complement (c'), neutralizes virus infectivity. in the absence of c', reaction of the antibody with our laboratory strain of sindbis, sb, increased the number of plaque-forming units (pfu) detected on baby hamster kidney (bhk) cells rather than neutralizing virus infectivity. the elevated titers of sb approa ... | 1988 | 3413988 |
| ultrastructure of the crystalline inclusion induced by tobacco etch virus visualized by freeze-etching. | | 1974 | 4834848 |
| electron microscopy of host cells infected with tobacco etch virus. 3. intranuclear modifications of leaves at an early stage of infection. | | 1966 | 5932835 |
| design of a new protease inhibitor by the manipulation of the bait region of alpha 2-macroglobulin: inhibition of the tobacco etch virus protease by mutant alpha 2-macroglobulin. | human alpha 2-macroglobulin (alpha 2m) inhibits a broad spectrum of proteases by changing its conformation and physically confining the enzyme. the inhibitory spectrum of alpha 2m is defined by a stretch of 39 amino acids, the bait region, located near the middle of the alpha 2m monomers. to investigate whether a new inhibitory specificity can be introduced by the manipulation of the bait region, recombinant alpha 2m (r alpha 2m) was produced in which the primary cleavage site was replaced by a ... | 1995 | 7492312 |
| distinct functions of capsid protein in assembly and movement of tobacco etch potyvirus in plants. | tobacco etch potyvirus engineered to express the reporter protein beta-glucuronidase (tev-gus) was used for direct observation and quantitation of virus translocation in plants. four tev-gus mutants were generated containing capsid proteins (cps) with single amino acid substitutions (r154d and d198r), a double substitution (dr), or a deletion of part of the n-terminal domain (delta n). each modified virus replicated as well as the parental virus in protoplasts, but was defective in cell-to-cell ... | 1994 | 7511101 |
| electron microscopic localization of atpase activity in tobacco cells infected by tobacco etch potyvirus and tobacco mosaic virus. | thin sections of leaves of plants infected by tobacco etch potyvirus (tev) or tobacco mosaic virus (tmv) were examined for the presence of atpase activity by electron microscopy. atpase activity was found as expected in mitochondria, chloroplasts and plasmalemma of both uninfected as well as cells infected by either tev or tmv. in the tev-infected cells, atpase activity was localized to virus-induced vesicles, endoplasmic reticulum and in some cells, to ribosomes attached to the er. in tmv-infec ... | 1995 | 7646342 |
| evidence that the potyvirus p1 proteinase functions in trans as an accessory factor for genome amplification. | the tobacco etch potyvirus (tev) polyprotein is proteolytically processed by three viral proteinases (nia, hc-pro, and p1). while the nia and hc-pro proteinases each provide multiple functions essential for viral infectivity, the role of the p1 proteinase beyond its autoproteolytic activity is understood poorly. to determine if p1 is necessary for genome amplification and/or virus movement from cell to cell, a mutant lacking the entire p1 coding region (delta p1 mutant) was produced with a modif ... | 1995 | 7745715 |
| requirement for hc-pro processing during genome amplification of tobacco etch potyvirus. | the helper component-proteinase (hc-pro) of tobacco etch potyvirus (tev) is a multifunctional protein with several known activities. the n-terminal region is required for aphid transmission and efficient genome amplification, the central region is required for long-distance movement in plants, and the c-terminal domain is a cysteine-type proteinase that autocatalytically cleaves between itself and the p3 protein. to investigate the requirement for hc-pro-mediated proteolysis during viral replica ... | 1995 | 7747479 |
| long-distance movement factor: a transport function of the potyvirus helper component proteinase. | transport of viruses from cell to cell in plants typically involves one or more viral proteins that supply dedicated movement functions. transport from leaf to leaf through phloem, or long-distance transport, is a poorly understood process with requirements differing from those of cell-to-cell movement. through genetic analysis of tobacco etch virus (tev; potyvirus group), a novel long-distance movement factor was identified that facilitates vascular-associated movement in tobacco. a mutation in ... | 1995 | 7780307 |
| complementation of tobacco etch potyvirus mutants by active rna polymerase expressed in transgenic cells. | a genetic complementation system was developed in which tobacco etch virus (tev) polymerase (nib)-expressing transgenic plants or protoplasts were inoculated with nib-defective tev mutants. a beta-glucuronidase (gus) reporter gene integrated into the genomes of parental and four mutant viruses was used to assay rna amplification. two mutants (termed vnn and ede) contained substitutions affecting the conserved "gdd" polymerase motif or a nuclear localization signal sequence, respectively; one (ad ... | 1995 | 7831310 |
| 5' proximal potyviral sequences mediate potato virus x/potyviral synergistic disease in transgenic tobacco. | the interaction of potato virus x (pvx) and potato virus y (pvy) in tobacco causes a synergistic disease characterized by a dramatic increase in symptom severity, a change in the regulation of pvx rna replication, and an increase in accumulation of pvx. in this study we demonstrate that pvx also interacts synergistically with three other members of the potyvirus group of plant viruses, tobacco vein mottling virus (tvmv), tobacco etch virus (tev), and pepper mottle virus. these synergisms resembl ... | 1995 | 7831814 |
| debilitation of plant potyvirus infectivity by p1 proteinase-inactivating mutations and restoration by second-site modifications. | tobacco etch virus (tev) encodes three proteinases that catalyze processing of the genome-encoded polyprotein. the p1 proteinase originates from the n terminus of the polyprotein and catalyzes proteolysis between itself and the helper component proteinase (hc-pro). mutations resulting in substitution of a single amino acid, small insertions, or deletions were introduced into the p1 coding sequence of the tev genome. deletion of the n-terminal, nonproteolytic domain of p1 had only minor effects o ... | 1995 | 7853492 |
| capsid protein determinants involved in cell-to-cell and long distance movement of tobacco etch potyvirus. | the tobacco etch potyvirus (tev) capsid protein (cp) is necessary for cell-to-cell and long distance transport of the virus in plants. in this study, the transport phenotypes of tev mutants containing cps with a substitution of the highly conserved ser122 (termed s122w) within the core domain, or with a deletion of sequences encoding 17 amino acid residues comprising most of the variable c-terminal domain (delta c), were analyzed. the s122w and delta c mutant genomes were amplified to levels com ... | 1995 | 7856075 |
| rna-mediated virus resistance in transgenic plants: exploitation of a cellular pathway possibly involved in rna degradation. | transgenic nicotiana tabacum cv. burley 49 plants were generated that express the 5' untranslated region of the tobacco etch potyvirus (tev) genome ligated to a mutated version of the tev coat protein gene sequence that rendered it untranslatable. eight different transgenic plant lines were analyzed for transgene expression and for resistance to tev. three different responses were noted when the transgenic plant lines were inoculated with tev: 1) some were highly resistant, and no virus replicat ... | 1994 | 7949323 |
| in vitro characterization of a cassette to accumulate multiple proteins through synthesis of a self-processing polypeptide. | the strategy for processing the polyprotein encoded by plant potyviruses has been mimicked by constructing an expression cassette based on the nuclear inclusion (nla) proteinase from tobacco etch virus (tev). this cassette (ppr01), includes the tev nla coding region flanked on each side by its heptapeptide cleavage sequence and cloning sites for the in frame insertion of two different open reading frames. ppr01 allows the synthesis, under the control of a single transcriptional promoter, of two ... | 1994 | 8123791 |
| the tobacco etch potyvirus 6-kilodalton protein is membrane associated and involved in viral replication. | the tobacco etch potyvirus (tev) genome encodes a polyprotein that is processed by three virus-encoded proteinases. although replication of tev likely occurs in the cytoplasm, two replication-associated proteins, vpg-proteinase (nuclear inclusion protein a) (nia) and rna-dependent rna polymerase (nuclear inclusion protein b) (nib), accumulate in the nucleus of infected cells. the 6-kda protein is located adjacent to the n terminus of nia in the tev polyprotein, and, in the context of a 6-kda pro ... | 1994 | 8139025 |
| release of proteins and peptides from fusion proteins using a recombinant plant virus proteinase. | an improved method for the production, cleavage, and purification of fusion proteins and peptides is described. the unique aspect of this method is dependent on the use of a proteinase from tobacco etch virus (tev). the proteinase used is a recombinant tev proteinase produced with a polyhistidine tract positioned at the amino terminus. the proteinase recognizes a specific, extended cleavage site sequence. the peptide or protein of interest is purified as a fusion protein with a tev proteinase cl ... | 1994 | 8179197 |
| specificity of replicase-mediated resistance to cucumber mosaic virus. | plants transformed with a nucleotide sequence coding for a truncated rna 2 replicase gene of the subgroup i strain of cucumber mosaic virus, fny-cmv, are resistant to cucumber mosaic disease. two resistant lines representing independent transformations in the original study have been propagated, and their progeny have been examined. resistance to fny-cmv was genetically integrated and was retained in the r4 generation. fourteen subgroup i cmv strains, 6 strains uncharacterized as to subgroup, an ... | 1994 | 8184532 |
| analysis of transgenic tobacco plants expressing a truncated form of a potyvirus coat protein nucleotide sequence. | transgenic nicotiana tabacum cv. burley 49 plants were generated which expressed a tobacco etch virus (tev) coat protein (cp) gene construct containing a stop codon positioned at codon 147. this gene construct was expected to produce a tev cp lacking the carboxy-terminal 118 amino acids of the full-length 264 amino acid cp. tev cp gene transcripts of the expected size could be detected in transgenic plants but the expected truncated cp could not be detected. ten independent transgenic lines expr ... | 1994 | 8204829 |
| internal cleavage and trans-proteolytic activities of the vpg-proteinase (nia) of tobacco etch potyvirus in vivo. | the nia protein of plant potyviruses is a bifunctional protein containing an n-terminal vpg domain and a c-terminal proteinase region. the majority of tobacco etch potyvirus (tev) nia molecules are localized to the nucleus of infected cells, although a proportion of nia is attached covalently as vpg to viral rna in the cytoplasm. a suboptimal cleavage site that is recognized by the nia proteinase is located between the two domains. this site was found to be utilized in the vpg-associated, but no ... | 1993 | 8230423 |
| genetic engineering of potyvirus resistance using constructs derived from the zucchini yellow mosaic virus coat protein gene. | three versions of the zucchini yellow mosaic virus (zymv) coat protein gene were engineered for expression in plants: the full-length coat protein sequence, the conserved core portion of the gene, and an antisense version. these constructs were introduced into muskmelon (cucumis melo) and tobacco plants (nicotiana tabacum) via agrobacterium tumefaciens-mediated transformation; gene expression was verified by northern and western analysis. transgenic r0 and r1 muskmelon plants expressing the full ... | 1993 | 8324251 |
| spontaneous mutagenesis of a plant potyvirus genome after insertion of a foreign gene. | the rna genome of tobacco etch potyvirus (tev) was engineered to express bacterial beta-glucuronidase (gus) fused to the virus helper component proteinase (hc-pro). it was shown previously that prolonged periods (approximately 1 month) of tev-gus propagation in plants resulted in the appearance of spontaneous deletion variants. nine deletion mutants were identified by nucleotide sequence analysis of 40 cdna clones obtained after polymerase chain reaction amplification. the mutants were missing b ... | 1993 | 8371351 |
| nuclear transport of tobacco etch potyviral rna-dependent rna polymerase is highly sensitive to sequence alterations. | the putative rna-dependent rna polymerase (nib protein) of tobacco etch potyvirus accumulates primarily in the nucleus of infected cells, although viral rna replication is suggested to occur in the cytoplasm. to understand the possible relationship between nib nuclear localization and its function, we have studied translocation of nib using gene fusion and plant transformation techniques. when expressed as a fusion with a cytoplasmic reporter protein, beta-glucuronidase (gus), nib efficiently di ... | 1993 | 8460496 |
| the tobacco etch viral 5' leader and poly(a) tail are functionally synergistic regulators of translation. | the 5' cap (m7gpppn) and the poly(a) tail of eukaryotic mrnas work in concert to establish an efficient level of translation in vivo. nevertheless, several mrnas naturally lack a cap or a poly(a) tail. determining how these messages effectively compete for the translational machinery not only reveals alternative mechanisms for translational competence, but can also underscore similarities between alternative mechanisms and the standard cap/poly(a) tail interaction. the genomic rna of tobacco etc ... | 1995 | 8522182 |
| nucleotide sequence of a strain of tobacco etch virus that does not cause tabasco pepper wilt. | | 1995 | 8560790 |
| genetic and biochemical dissection of transgenic rna-mediated virus resistance. | rna-mediated virus resistance has been observed in transgenic plants at varying frequencies, suggesting that a nuclear requirement or other pre-condition must be met. this study was undertaken to characterize genetically transgenes that confer a highly resistant state to infection by tobacco etch virus (tev). transgenic tobacco line 2rc-6.13, expressing an untranslatable mrna containing the tev coat protein open reading frame, had three distinct transgene integration events that segregated as tw ... | 1996 | 8597662 |
| loss of potyvirus transmissibility and helper-component activity correlate with non-retention of virions in aphid stylets. | the hypothesis that loss of aphid transmissibility of potyvirus mutants is due to non-retention of virions in the mouthparts was tested by feeding aphids through membranes on purified virions of aphid transmissible (at or hat) and non-aphid-transmissible (nat) tobacco vein mottling virus (tvmv) or tobacco etch virus (tev), in the presence of functional [potato virus y (pvy) hc or tvmv hc] or non-functional (pvc hc) helper component (hc). tvmv virions were detected, by electron microscopic examin ... | 1996 | 8609482 |
| site-specific proteolysis of the escherichia coli seca protein in vivo. | a seven-amino-acid cleavage site specific for tobacco etch virus (tev) protease was introduced into seca at two separate positions after amino acids 195 and 252. chromosomal wild-type seca was replaced by these seca constructs. simultaneous expression of tev protease led to cleavage of both seca derivatives. in the functional seca dimer, proteolysis directly indicated surface exposure of the tev protease cleavage sites. cleavage of seca near residue 195 generated an unstable proteolysis product ... | 1996 | 8631693 |