title: The Ca(2+)-sensitizing component of smooth muscle thin filaments: properties of regulatory factors that interact with caldesmon.
abstract: We have investigated the nature of the native Ca(2+)-sensitizing factor of smooth muscle native thin filaments. Two different types of preparation yielded protein mixtures which consistently conferred Ca(2+)-sensitivity on thin filaments reconstituted from aorta actin, tropomyosin and caldesmon. These new preparations produced a good model of native thin filaments, unlike previous systems reconstituted with calmodulin or S. 100. We conclude that the Ca(2+)-sensitizing factor is a protein of molecular weight in the range 15 kDa - 40 kDa which is heat-labile and which has properties distinct from calponin, S. 100 or calmodulin.
authors.affiliation: Department of Cardiac Medicine, National Heart and Lung Institute, London, England.
authors.forename: K
authors.initials: K
authors.lastname: Pritchard
authors.forename: S B
authors.initials: SB
authors.lastname: Marston
mesh_terms: D000205:Actomyosin / Q000302:isolation & purification; D000818:Animals; D001011:Aorta; D002118:Calcium / Q000494:pharmacology*; D002135:Calcium-Binding Proteins / Q000302:isolation & purification / Q000494:pharmacology; D002147:Calmodulin / Q000494:pharmacology; D002148:Calmodulin-Binding Proteins / Q000037:antagonists & inhibitors / Q000302:isolation & purification / Q000502:physiology*; D002417:Cattle; D002845:Chromatography; D002850:Chromatography, Gel; D006358:Hot Temperature; D009124:Muscle Proteins / Q000502:physiology*; D009131:Muscle, Smooth, Vascular / Q000737:chemistry*; D012756:Sheep; D014335:Tropomyosin / Q000302:isolation & purification
chemical_list: D002135:Calcium-Binding Proteins; D002147:Calmodulin; D002148:Calmodulin-Binding Proteins; D009124:Muscle Proteins; D014335:Tropomyosin; D000205:Actomyosin; D002118:Calcium