title: Chaperone-like activity revealed in the matricellular protein SPARC.
abstract: SPARC (Secreted Protein, Acidic and Rich in Cysteine) is a matricellular glycoprotein that modulates cell proliferation, adhesion, migration, and extracellular matrix (ECM) production. In this report chaperone-like activity of SPARC was identified in a thermal aggregation assay in vitro. Ultraviolet circular dichroism (UVCD) spectroscopy determined that SPARC was stable at temperatures up to 50 degrees C. Unfolding and aggregation of the chaperone target protein, alcohol dehydrogenase (ADH), were initiated at 50 degrees C. SPARC inhibited the thermal aggregation of ADH in a concentration-dependent manner, with maximal inhibition at a 1:4 molar ratio of SPARC:ADH. Synergy between the chaperone-like activities of SPARC and alphaB-crystallin, a small heat shock protein and molecular chaperone in the lens, was observed in SPARC-alphaB-crystallin double -/- mice.
authors.affiliation: Department of Biological Structure, University of Washington, Seattle, WA 98195-7420, USA
authors.forename: Ryan O
authors.initials: RO
authors.lastname: Emerson
authors.forename: E Helene
authors.initials: EH
authors.lastname: Sage
authors.forename: Joy G
authors.initials: JG
authors.lastname: Ghosh
authors.forename: John I
authors.initials: JI
authors.lastname: Clark
mesh_terms: D000426:Alcohol Dehydrogenase / Q000737:chemistry / Q000378:metabolism; D000818:Animals; D002448:Cell Adhesion / Q000502:physiology; D002465:Cell Movement / Q000502:physiology; D002942:Circular Dichroism; D005109:Extracellular Matrix / Q000737:chemistry* / Q000378:metabolism; D006358:Hot Temperature; D051379:Mice; D018345:Mice, Knockout; D018832:Molecular Chaperones / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D015676:Osteonectin / Q000737:chemistry* / Q000172:deficiency / Q000378:metabolism; D011489:Protein Denaturation; D017510:Protein Folding; D038201:alpha-Crystallins / Q000737:chemistry / Q000378:metabolism; D038204:beta-Crystallins / Q000737:chemistry / Q000378:metabolism
chemical_list: D018832:Molecular Chaperones; D015676:Osteonectin; D038201:alpha-Crystallins; D038204:beta-Crystallins; D000426:Alcohol Dehydrogenase