title: Phosphorylation of chicken gizzard myosin and the Ca2+-sensitivity of the actin-activated Mg2+-ATPase.
abstract: A method is described for the preparation of partially and fully phosphorylated chicken gizzard myosin. When fully phosphorylated it possessed an actin-activated Mg2+-ATPase of similar specific activity to that of mammalian skeletal muscle myosin. The Mg2+-ATPase activity of these preparations was related in a non-linear fashion to increasing phosphorylation of the P light chain. When P light chain phosphorylation occurred during enzymic assay the Mg2+-ATPase activity remained constant. Fully phosphorylated preparations of gizzard myosin possessed an actin-activated Mg2+-ATPase that was not Ca2+-sensitive, whereas the Mg2+-ATPase of partially phosphorylated myosin preparations was Ca2+-sensitive.
mesh_terms: D000199:Actins / Q000494:pharmacology*; D000251:Adenosine Triphosphatases / Q000378:metabolism*; D000818:Animals; D017301:Ca(2+) Mg(2+)-ATPase; D002118:Calcium / Q000494:pharmacology*; D002645:Chickens; D004789:Enzyme Activation / Q000187:drug effects; D005895:Gizzard, Avian / Q000201:enzymology / Q000378:metabolism*; D009218:Myosins / Q000378:metabolism*; D010766:Phosphorylation
chemical_list: D000199:Actins; D000251:Adenosine Triphosphatases; D017301:Ca(2+) Mg(2+)-ATPase; D009218:Myosins; D002118:Calcium