Analysis in vivo of GRP78-BiP/substrate interactions and their role in induction of the GRP78-BiP gene.
The endoplasmic reticulum (ER)-localized chaperone protein, GRP78-BiP, is involved in the folding and oligomerization of secreted and membrane proteins, including the simian virus 5 hemagglutinin-neuraminidase (HN) glycoprotein. To understand this interaction better, we have constructed a series of HN mutants in which specific portions of the extracytoplasmic domain have been deleted. Analysis of these mutant polypeptides expressed in CV-1 cells have indicated that GRP78-BiP binds to selective sequences in HN and that there exists more than a single site of interaction. Mutant polypeptides have been characterized that are competent and incompetent for association with GRP78-BiP. These mutants have been used to show that the induction of GRP78-BiP synthesis due to the presence of nonnative protein molecules in the ER is dependent on GRP78-BiP complex formation with its substrates. These studies have implications for the function of the GRP78-BiP protein and the mechanism by which the gene is regulated.
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Department of Biochemistry, Molecular Biology, and Cell Biology, Northwestern University, Evanston, Illinois 60208-3500.
Watowich
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Lamb
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D000818:Animals; D001692:Biological Transport / Q000235:genetics; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D004274:DNA, Recombinant / Q000235:genetics; D004721:Endoplasmic Reticulum / Q000378:metabolism; D000091342:Endoplasmic Reticulum Chaperone BiP; D005786:Gene Expression Regulation / Q000502:physiology; D015707:HN Protein / Q000235:genetics / Q000378:metabolism*; D006360:Heat-Shock Proteins; D018832:Molecular Chaperones; D009154:Mutation / Q000502:physiology; D010449:Peptide Mapping; D011485:Protein Binding; D012333:RNA, Messenger / Q000032:analysis
D002352:Carrier Proteins; D004274:DNA, Recombinant; D000091342:Endoplasmic Reticulum Chaperone BiP; D015707:HN Protein; D006360:Heat-Shock Proteins; D018832:Molecular Chaperones; D012333:RNA, Messenger