Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0019158 (hepatitis)
 30,205 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have investigated the intracellular localization of several of the proteolytic cleavage products derived from the 5' portion of mouse hepatitis virus (MHV) gene 1. Antisera UP1 recognizes the N-terminal ORF1a cleavage product p28. Immunofluorescent staining of cells with this antisera resulted in a diffuse punctate pattern of cytoplasmic staining, indicating that this protein is widely distributed in the cytoplasm. Immunofluorescent staining of infected cells with antisera which recognize polypeptides p240 and p290 stained discrete vesicular perinuclear structures suggesting that these proteins localized to the Golgi. This was confirmed by double immunofluorescent staining of BHK cells expressing the MHV receptor (BHK-R) with a Golgi specific antibody in addition to our anti-MHV ORF1a antibodies. Antisera UP102 recognizes p28 and the immediately downstream p65 gene product. Double immunofluorescent staining of MHV infected BHK-R cells with UP102 labeled discrete vesicular structures overlapping the Golgi complex. In addition there was punctate staining more widely distributed in the cytoplasm. The simplest explanation for this pattern is that p65 is also localized to the Golgi region of the cell, whereas p28 is more widespread. Plasmids containing the first 4.7 and 6.75 kb of ORF 1a have been expressed using the coupled vaccinia virus-T7 polymerase system. Images obtained by immunofluorescent staining of transfectants with our anti-ORF1a antisera are similar to those obtained during infection with A59. These studies indicate that the signals which direct p290 to the Golgi are likely contained between the C-terminus of p28 and ORF1a residue 1494.
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PMID:Intracellular localization of polypeptides encoded in mouse hepatitis virus open reading frame 1A. 883 Apr 88

We have investigated the intracellular localization of proteolytic cleavage products encoded in the 5' portion of mouse hepatitis virus (MHV) gene 1. Immunofluorescent labeling of cells with an antiserum which recognizes p28, the ORF1a N-terminal cleavage product, resulted in widespread somewhat granular cytoplasmic staining, indicating that this protein is widely distributed in the cytoplasm of MHV-infected, but not control uninfected cells. Immunofluorescent staining of infected cells with antisera which recognize the downstream polypeptides, p65, p240 and p290 labeled discrete vesicular perinuclear structures. Double immunofluorescent labeling of BHK cells expressing the MHV receptor (BHK(MHVR1)) and infected with MHV-A59 with a Golgi-specific anti-mannosidase II monoclonal antibody and with antiserum recognizing each of these anti-MHV ORF1a polypeptides, showed that the p240 and p290 polypeptides were localized in discrete vesicular structures that overlapped the Golgi complex. Labeling with antibodies specific for p65 colocalized with the Golgi region, and showed staining of the perinuclear cytoplasm as well. Plasmids containing sequences contained in the first 6.75 kb of ORF1a have been expressed using the coupled vaccinia virus-T7 polymerase system. Immunofluorescent labeling of transfectants with the anti-ORF1a antisera showed patterns of antigen distribution similar to those observed in cells infected with MHV-A59. A deletion analysis with constructs containing only portions of the ORF1a sequence indicated that 303 amino acids containing the first papain-like protease domain (PLP-1) was sufficient to associate this protein with the Golgi.
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PMID:Localization of mouse hepatitis virus open reading frame 1A derived proteins. 1006 1

The largest replicative protein of coronaviruses is known as p195 in the avian infectious bronchitis virus (IBV) and p210 (p240) in the mouse hepatitis virus. It is autocatalytically released from the precursors pp1a and pp1ab by one zinc finger-containing papain-like protease (PLpro) in IBV and by two paralogous PLpros, PL1pro and PL2pro, in mouse hepatitis virus. The PLpro-containing proteins have been recently implicated in the control of coronavirus subgenomic mRNA synthesis (transcription). By using comparative sequence analysis, we now show that the respective proteins of all sequenced coronaviruses are flanked by two conserved PLpro cleavage sites and share a complex (multi)domain organization with PL1pro being inactivated in IBV. Based upon these predictions, the processing of the human coronavirus 229E p195/p210 N terminus was studied in detail. First, an 87-kDa protein (p87), which is derived from a pp1a/pp1ab region immediately upstream of p195/p210, was identified in human coronavirus 229E-infected cells. Second, in vitro synthesized proteins representing different parts of pp1a were autocatalytically processed at the predicted site. Surprisingly, both PL1pro and PL2pro cleaved between p87 and p195/p210. The PL1pro-mediated cleavage was slow and significantly suppressed by a non-proteolytic activity of PL2pro. In contrast, PL2pro, whose proteolytic activity and specificity were established in this study, cleaved the same site efficiently in the presence of the upstream domains. Third, a correlation was observed between the overlapping substrate specificities and the parallel evolution of PL1pro and PL2pro. Collectively, our results imply that the p195/p210 autoprocessing mechanisms may be conserved among coronaviruses to an extent not appreciated previously, with PL2pro playing a major role. A large subset of coronaviruses may employ two proteases to cleave the same site(s) and thus regulate the expression of the viral genome in a unique way.
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PMID:The autocatalytic release of a putative RNA virus transcription factor from its polyprotein precursor involves two paralogous papain-like proteases that cleave the same peptide bond. 1143 76

Proteolytic processing of the mouse hepatitis virus strain A59 (MHV-A59) replicase gene product, pp1a, results in polypeptides p28, p65, p50, and p240 in infected cells. Based on previously identified p28 and p65 cleavage sites, a p50 cleavage site was proposed to occur between Ala-1262 and Ala-1263. Results of mutagenesis and in vitro cleavage assays show that PLP-1 was able to cleave in trans when the proposed p50 cleavage sequence replaced the p28 cleavage sequence. Mutagenesis was also used to investigate cleavage between Gly-904 and Val-905, a cleavage site predicted to produce a precursor of p65, p72, that was detected in cells infected with MHV strain JHM, but not with MHV-A59. No cleavage could be detected using substrate that carried both the p65 site and the predicted p72 cleavage sequence. Thus, it appeared that PLP-1 could recognize the proposed p50 sequence but not the predicted p72 site under the in vitro conditions used.
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PMID:Further in vitro characterization of mouse hepatitis virus papain-like proteinase 1: cleavage sequence requirements within pp1a. 1193 66