title: Alpha-crystallin, a molecular chaperone, forms a stable complex with carbonic anhydrase upon heat denaturation.
abstract: Alpha-crystallin, a major eye lens protein of vertebrates has been characterized as a molecular chaperone based on its ability to inhibit the aggregation of proteins undergoing thermal denaturation (Horwitz, J., Proc. Natl. Acad. Sci. USA 1992, 89, 10449-10453). To understand the mechanisms underlying this chaperone-like activity, the present study addressed molecular interactions between alpha-crystallin and its target proteins. Using carbonic anhydrase as a model target protein, we demonstrate complex formation between the 2 proteins upon heating, as assessed by the criteria of agarose gel electrophoresis, immunoprecipitation, ultrafiltration and gel filtration chromatography. The complex of alpha-crystallin and carbonic anhydrase is stable, at room temperature and at 4 degrees C, for over 18 hours, and is non-covalent in nature. The results also indicate that alpha-crystallin binds the early non-native form of the target protein.
authors.affiliation: Laboratory of Mechanisms of Ocular Diseases, National Eye Institute, National Institutes of Health, Bethesda, MD 20892.
authors.forename: P V
authors.initials: PV
authors.lastname: Rao
authors.forename: J
authors.initials: J
authors.lastname: Horwitz
authors.forename: J S
authors.initials: JS
authors.lastname: Zigler
mesh_terms: D000818:Animals; D002256:Carbonic Anhydrases / Q000737:chemistry*; D002417:Cattle; D018833:Chaperonins; D003459:Crystallins / Q000737:chemistry*; D006358:Hot Temperature; D066298:In Vitro Techniques; D046911:Macromolecular Substances; D011485:Protein Binding; D011489:Protein Denaturation; D011506:Proteins / Q000737:chemistry*
chemical_list: D003459:Crystallins; D046911:Macromolecular Substances; D011506:Proteins; D018833:Chaperonins; D002256:Carbonic Anhydrases