title: Fluorescence polarization study on Ca2+-sensitivity of conformational changes in F-actin induced by the formation of F-actin-subfragment-1 complex.
abstract: Ca2+-dependent conformational changes in F-actin during myosin subfragment-1 binding with thin filament (in the absence of troponin and tropomyosin) were found in myosin-free ghost fibres by polarized UV microscopy. The pattern of the conformational changes in F-actin changed cooperatively within the range of free Ca2+ concentrations from 10(-7) mol/l to 10(-6) mol/l. It should be suggested that in skeletal muscle of vertebrates there exists a myosin-linked modulation of contraction by Ca2+.
mesh_terms: D000199:Actins; D000818:Animals; D002118:Calcium / Q000494:pharmacology*; D004492:Edetic Acid / Q000494:pharmacology; D005454:Fluorescence Polarization; D046911:Macromolecular Substances; D008274:Magnesium / Q000494:pharmacology; D009132:Muscles / Q000648:ultrastructure*; D015879:Myosin Subfragments; D009218:Myosins; D010446:Peptide Fragments; D011487:Protein Conformation / Q000187:drug effects; D011817:Rabbits
chemical_list: D000199:Actins; D046911:Macromolecular Substances; D015879:Myosin Subfragments; D010446:Peptide Fragments; D004492:Edetic Acid; D009218:Myosins; D008274:Magnesium; D002118:Calcium