Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:Q07644 (polypeptide)
 72,197 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The mechanism of inhibition of Moloney leukemia virus by N-methylisatin-beta-4',4'-diethylthiosemicarbazone was studied. Experiments that used [3H]leucine for short-pulse labeling in the presence of the drug resulted in a 71% inhibition in the synthesis of Pr-80, the polypeptide precursor of the gag viral proteins. The radioactive pulse products of the polypeptide precursors after a further 2-h chase period showed a normal cleavage of the precursors, with the formation of a reduced amount of final mature viral structural proteins. The experimental evidence indicated that at the inhibitory concentration of 17 microM N-methylisatin-beta-4',4'-diethylthiosemicarbazone, the amount of intracellular viral RNA was not affected, whereas the activities of reverse transcriptase and the other viral protein syntheses were suppressed.
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PMID:Inhibition of the synthesis of Moloney leukemia virus structural proteins by N-methylisatin-beta-4',4'-diethylthiosemicarbazone. 608 72

The gag and env gene products of human T-cell leukemia virus (HTLV) were identified with rabbit antisera against the synthetic peptides and a polypeptide produced in Escherichia coli, which corresponded to parts of the proteins predicted from the nucleotide sequence of HTLV [M. Seiki, S. Hattori, Y. Hirayama, and M. Yoshida (1983). Proc. Natl. Acad. Sci. USA 80, 3618-3622]. Viral proteins were detected by immunoprecipitation in two HTLV-producing cell lines. The precursor of gag products was a protein with an apparent molecular weight of 53,000 (Pr53), and was shown to be processed into three mature gag proteins, p19, p24, and p15, in this order, from the 5' end of the gag gene. The processing sites were confirmed to be the same as those predicted from the nucleotide sequence. The env gene product was identified as a glycoprotein of 62,000 Da (gp62), which was processed into gp46 and p20E. All the viral antigens described above were also detected with sera from ATL patients, indicating that all these proteins are expressed in the patients.
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PMID:Identification of gag and env gene products of human T-cell leukemia virus (HTLV). 608 48

Sera of individuals infected with adult T-cell leukaemia virus (ATLV) react predominantly with the polypeptides gp68, p24 and p19. These polypeptides were isolated from ATLV-infected MT-2 cells and virus. The radioiodinated polypeptides were used to quantify respective antibodies in individual ATLV carrier sera. Heteroantisera prepared in rabbits against isolated polypeptides facilitated studies on the biosynthesis of the core and envelope polypeptides of ATLV. Pulse-chase experiments revealed a polypeptide of mol. wt. 48 000 (48K) as the precursor to the core polypeptides p24 and p19. A 28K polypeptide related to p19 appeared to be an early side-product of the gag gene or a translate of a defective viral message. Antiserum to the putative env gene product gp68 recognized gp68, gp66 and small amounts of gp62. In tunicamycin-treated cells gp68, gp66 and gp62 were no longer synthesized, but a 54K polypeptide reacted with antiserum to gp68. Polypeptide p54 is structurally related to gp68 and therefore apparently represents the unglycosylated form of gp68. Moreover, the apparent mol. wt. of p54 and p48 agree with those predicted for respective env and gag precursors from the nucleotide sequence of an ATLV provirus.
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PMID:Precursor polypeptides of adult T-cell leukaemia virus: detection with antisera against isolated polypeptides gp68, p24 and p19. 609 96

Gel filtration chromatography of disrupted bovine leukaemia virus (BLV) resulted in the isolation of the 25000 mol. wt. major internal protein (p25), two previously uncharacterized proteins of mol. wt 65000 (p65) and 12000 (p12), and a mixture of p12 and a protein of mol. wt. 15000 (p15). The p65 protein does not bind to concanavalin A and its antigenicity is ether resistant. Therefore, this polypeptide is different from the previously described glycoprotein associated with BLV. Radioimmunoprecipitation and competitive radioimmunoassays indicated that the p65 protein shares antigenic determinants with the p25, p15 and p12 proteins, respectively. Furthermore, tryptic peptide mapping demonstrated that p65 contains p25, p15, p12 and a BLV protein of mol. wt. 10000 (p10). These results are consistent with the view that p65 is the precursor of gag gene-derived core proteins of BLV.
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PMID:Detection of a precursor-like protein of bovine leukaemia virus structural polypeptides in purified virions. 615 29

The McDonough (SM), Gardner-Arnstein (GA), and Snyder-Theilen (ST) strains of feline sarcoma virus (FeSV) code for high-molecular-weight polyproteins that contain varying amounts of the amino-terminal region of the FeLV gag gene-coded precursor protein and a polypeptide(s) of an as yet undetermined nature. The SM-FeSV primary translational product is a 180,000-dalton polyprotein which is immediately processed into a highly unstable 60,000-dalton molecule containing the p15-p12-p30 fragment of the FeLV gag gene-coded precursor protein and a 120,000-dalton FeSV-specific polypeptide. The GA- and ST-FeSV genomes code for polyproteins of 95,000 and 85,000 daltons, respectively, which in addition to the amino-terminal moiety (p15-12 and a portion of p30) of the FeLV gag gene-coded precursor protein also contain FeSV-specific polypeptides. However, the GA- and ST-FeSV polyproteins appear to be relatively stable molecules (half-lives of around 16 h) and are not significantly processed into smaller polypeptides. Immunological and biochemical analysis of each of the above FeSV translational products revealed that the sarcoma-specific regions of the GA- and ST-FeSV polyproteins are antigenically cross-reactive and exhibit common methionine-containing peptides. These findings favor the concept that these sarcoma-specific polypeptides are coded for by the similar subsets of cellular sequences incorporated into the GA- and ST-FeSV genomes during the generation of these transforming agents.
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PMID:Biochemical and immunological characterization of polyproteins coded for by the McDonough, Gardner-Arnstein, and Snyder-Theilen strains of feline sarcoma virus. 615 48

We have studied the biosynthesis of avian retrovirus proteins related to reverse transcriptase in permissive avian embryonic cells. Analysis of immune precipitates from avian sarcoma virus (ASV)-infected cells demonstrated the presence of the 180,000-dalton gag-pol "read-through" protein (Pr180gag-pol) and a 130,000-dalton polypeptide (Pr130gag-pol). Pr130gag-pol was found, in serological and peptide mapping studies, to consist primarily of sequences related to reverse transcriptase and the gag-encoded protein p15. Pr180gag-pol was found to be phosphorylated, whereas Pr130gag-pol was not. In addition, only Pr180gag-pol but not Pr130gag-pol was susceptible to cleavage with the virion protease p15. Although the structure of Pr130gag-pol would suggest that it is generated by removal of a portion of the gag region from Pr180gag-pol, an analysis of labeling kinetics has failed to demonstrate unequivocally whether Pr130gag-pol is a cleavage product of Pr180gag-pol or a primary translation product. We were repeatedly unable to detect either Pr180gag-pol or Pr130gag-pol in virus particles released from the cell, whereas both beta and alpha subunits were readily observed. Several presumed intermediates between Pr130gag-pol and the beta subunit of reverse transcriptase were also observed in virions. These studies indicate cleavage of polyemrase precursors at the time of virus budding. On the basis of these data, we present a processing scheme for the generation of reverse transcriptase subunits. We have also examined reverse transcriptase biosynthesis in cells producing two mutants that fail to package the enzyme. Previous work showed that integrated proviruses of both mutants are missing DNA sequences in pol: one mutant, PH9 (Mason et al., J. Virol. 30:132-140, 1979), contains a deletion near the 3' end of pol, whereas the other, SE52d (linial et al., Virology 87:130-141, 1978), may have inserted a host cell sequence near the 5' end of pol. Neither mutant synthesized Pr180gag-pol or Pr130gag-pol, but instead produced novel proteins comprised of sequences shared with gag proteins plus a region antigenically related to reverse transcriptase. Both proteins were defective as precursors to reverse transcriptase. Whereas Pr180gag-pol and Pr130gag-pol were precipitated by an antiserum raised against p32 (a virion protein derived from the portion of the beta subunit removed during processing of beta to alpha [Schiff and Grandgenett, J. Virol. 28:279-291, 1978]), the novel protein synthesized by PH9 ws not precipitated. This suggets that the alpha subunit is generated by a COOH-terminal cleavage of the beta subunit.
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PMID:Synthesis and processing of polymerase proteins of wild-type and mutant avian retroviruses. 616 Feb 63

Visna virus is a retrovirus which replicates in fibroblast-like cells of the sheep choroid plexus through a lytic cycle. Visna virions contain three major low-molecular-weight proteins (p30, p16, and p14) which, together with the genomic RNA and several molecules of reverse transcriptase, constitute the core structure of the virions. The core is surrounded by an envelope containing a major glycoprotein (gp135). By analogy with the oncoviruses, these three groups of structural proteins (i.e., the internal proteins, the envelope glycoprotein, and the reverse transcriptase) are probably encoded by the gag, env, and pol genes, respectively. To elucidate the genetic organization of the visna virus genome and its expression, we studied the synthesis of viral proteins in infected sheep choroid plexus cells. Intracellular viral proteins were detected by immunoprecipitation of pulse-labeled cell extracts with monospecific sera raised against p30, p16, and gp135 and resolution of the proteins by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Immunoprecipitation with anti-p30 and anti-p16 sera allowed the characterization of the 55,000-dalton polypeptide precursor to internal virion proteins p30, p16, and p14 (Pr55(gag)). Tryptic peptide mapping confirmed the precursor-product relationship between Pr55(gag) and the three internal proteins. In addition, a gag-related polypeptide of 150,000 daltons was also detected. This polypeptide, which was less abundant than Pr55(gag), is a likely precursor to the viral reverse transcriptase (Pr150(gag-pol)). Pr55(gag) and Pr150(gag-pol) are not glycosylated. The precursor related to major envelope protein gp135 is a glycosylated polypeptide with an average molecular weight of 150,000 (gPr150(env)). Pulse-chase experiments indicated that gPr150(env) matures into glycoprotein gp135 intracellularly; however, gp135 was never preponderant in cell extracts. The non-glycosylated from of gPr150(env), which accumulated in the presence of 2-deoxy-d-glucose, appeared as a polypeptide of about 100,000 daltons. These results indicated that visna virus codes for the largest non-glycosylated env-related precursor among all of the retroviruses and therefore probably contains the largest env gene.
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PMID:Precursor polypeptides to structural proteins of visna virus. 617 45

We studied intracellular avian gag proteins (internal structural proteins of virions) in several mammalian cell lines transformed by Rous sarcoma virus. All lines examined contain gag antigens as determined by radioimmune assay. We used the techniques of protein blotting from polyacrylamide gels, which detects nanogram quantities of viral protein, to investigate the size of intracellular viral polypeptides. All of the lines that contained enough viral protein to be amenable to this type of analysis synthesized Pr76, the avian sarcoma virus gag precursor polypeptide, but failed to process it into mature virion proteins. In some cell lines, the recovery of Pr76 was greatly enhanced by the addition of a mixture of protease inhibitors, including the sulfhydryl-blocking reagent N-ethylmaleimide, to the lysis buffer. At least several of the mammalian cells also synthesized a viral polypeptide the size of Pr180, the precursor to reverse transcriptase. Since Rous sarcoma virus does not replicate or replicates extremely poorly in mammalian cells, the lack of processing suggests that cleavage and virion assembly are invariably associated.
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PMID:Avian sarcoma virus gag precursor polypeptide is not processed in mammalian cells. 618 52

Antibodies to a synthetic undecapeptide (NH2-Cys-Glu-Asn-Pro-Ser-Gln-Phe-Tyr-Glu-Arg-Leu-COOH), the sequence (except cysteine) of which was deduced from a previously reported cloned human retroviral gag-gene-related DNA sequence erv-1, were raised in rabbits. In immunohistochemical staining these antibodies reacted with normal human first-trimester placentas and with blighted ova and benign and malignant trophoblastic tumors (hydatidiform and destructive moles, choriocarcinomas) but not with any other normal embryonic or adult tissues tested. In all tissues the reactivity was mainly confined to cells with trophoblastic morphology. In immunoblotting the antibody detected an Mr 75,000 polypeptide in syncytiotrophoblasts isolated from first-trimester placentas and in three different lines of cultured choriocarcinoma cells. The undecapeptide blocked the reactivity of the antibody.
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PMID:Human placental syncytiotrophoblastic Mr 75,000 polypeptide defined by antibodies to a synthetic peptide based on a cloned human endogenous retroviral DNA sequence. 620 38

Avian erythroblastosis virus (AEV) RNA rescued from nonproducer cells by superinfection with a helper virus is translated into three polypeptides in the messenger-dependent rabbit reticulocyte lysate. A 75,000 molecular weight polypeptide (P75AEV) is synthesized from 28S RNA and is encoded by the 5' section of the AEV RNA, including gag-related and AEV-specific sequences. The P75AEV synthesized in infected cells and the P75AEV synthesized in the cell-free system are electrophoretically identical. A 44,000 molecular weight polypeptide (P44AEV) is synthesized from 20-24S RNA, apparently from the 3' section of the AEV-specific RNA sequence. A minor 37,000 molecular weight polypeptide (P37AEV) is synthesized from 20S AEV RNA. A comparison is drawn between the cell-free products of MC29 and AEV RNAs.
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PMID:Cell-free translation of avian erythroblastosis virus RNA. 624 60


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