Heat shock protein (hsp90) interacts with smooth muscle calponin and affects calponin-binding to actin

• Published in: Biochimica et biophysica acta Vol. 1476; no. 2; pp. 300 - 310
• Main Authors: Ma, YuShu, Bogatcheva, Natalia V, Gusev, Nikolai B
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 09.02.2000
• Subjects: Actin; Actins - metabolism; Animals; Binding Sites; Calcium-Binding Proteins - metabolism; Calponin; Calponins; Hsp90; HSP90 Heat-Shock Proteins - metabolism; Microfilament Proteins; Muscle, Smooth - metabolism; Protein Binding; Hsp90; CH-domain, calponin homology domain; Calponin; Hsp90, heat shock protein with molecular mass 90 kDa; Actin
• ISSN: 0167-4838; 0006-3002; 1879-2588; 1878-2434
• DOI: 10.1016/S0167-4838(99)00250-2

Interaction of smooth muscle calponin with 90 kDa heat shock protein (hsp90) was analyzed by means of native gel electrophoresis and affinity chromatography. Under conditions used, calponin and hsp90 form a complex with an apparent dissociation constant in the micromolar range. The major hsp90-binding site is located in the N-terminal (residues 7–144) part of calponin. Addition of calponin to actin-tropomyosin complex results in formation of actin bundles. Hsp90 partially prevents bundle formation without affecting the molar ratio calponin/actin in single actin filaments or actin bundles. At low ionic strength, calponin induces polymerization of G-actin. Hsp90 decreases calponin-induced polymerization of G-actin. It is supposed that hsp90 may be involved in the assembly of actin filaments.