title: Interaction of heavy chain binding protein (BiP/GRP78) with adenine nucleotides.
abstract: Immunoglobulin heavy chain binding protein (BiP/GRP78) is a resident endoplasmic reticulum protein that binds tightly to a number of incompletely assembled or aberrant proteins. BiP also binds ATP and can be purified by ATP affinity chromatography. Here we show that an ATPase activity co-purifies with BiP prepared from canine pancreas. The BiP-associated ATPase has a high affinity for ATP but a low turnover number, suggesting a regulatory, rather than an enzymatic role. We also show that submicromolar levels of ATP or ADP decrease the rate of adsorption of [125I]BiP to nitrocellulose filters coated with protein or non-ionic detergents. In contrast, micromolar levels of AMP increase the rate of adsorption. Furthermore, ATP and ADP decrease the susceptibility of BiP to proteolytic degradation, whereas AMP was found to enhance degradation slightly. Adenine nucleotides may therefore induce or stabilize different conformations of BiP even when ATP hydrolysis does not occur.
authors.affiliation: Department of Biochemistry and Biophysics, University of California, San Francisco 94143-0448.
authors.forename: C K
authors.initials: CK
authors.lastname: Kassenbrock
authors.forename: R B
authors.initials: RB
authors.lastname: Kelly
mesh_terms: D000227:Adenine Nucleotides / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000378:metabolism; D000327:Adsorption; D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism*; D004285:Dogs; D000091342:Endoplasmic Reticulum Chaperone BiP; D006360:Heat-Shock Proteins; D066298:In Vitro Techniques; D018832:Molecular Chaperones; D010179:Pancreas / Q000276:immunology / Q000378:metabolism; D010447:Peptide Hydrolases; D011487:Protein Conformation; D013499:Surface Properties
chemical_list: D000227:Adenine Nucleotides; D002352:Carrier Proteins; D000091342:Endoplasmic Reticulum Chaperone BiP; D006360:Heat-Shock Proteins; D018832:Molecular Chaperones; D000255:Adenosine Triphosphate; D010447:Peptide Hydrolases