title: Non-correlation of phosphorylation of the P-light chain and the actin activation of the ATPase of chicken gizzard myosin.
abstract: 1. The enzymic properties of myosin isolated from chicken gizzard by three different methods have been compared. 2. Although the specific Ca2+-stimulated ATPases of all preparations were similar and high, there were significant differences in the specific activities of the Mg2+-stimulated actomyosin ATPases. 3. There was no direct correlation between the Mg2+-stimulated actomyosin ATPase activity and the extent of P-light-chain phosphorylation in any of the three myosin preparations. 4. A fraction that activates the Mg2+-stimulated actomyosin ATPase of gizzard muscle has been isolated  from a gizzard muscle filament preparation. 5. The activator was specific for the Mg2+-activated actomyosin ATPase of smooth muscle. 6. The activator required the addition of calmodulin for full effect.
mesh_terms: D000205:Actomyosin / Q000378:metabolism*; D000251:Adenosine Triphosphatases / Q000378:metabolism*; D000818:Animals; D017301:Ca(2+) Mg(2+)-ATPase; D002147:Calmodulin / Q000494:pharmacology; D002498:Centrifugation; D002645:Chickens; D004789:Enzyme Activation; D005895:Gizzard, Avian / Q000378:metabolism; D066298:In Vitro Techniques; D009130:Muscle, Smooth / Q000201:enzymology; D009218:Myosins / Q000378:metabolism*; D010766:Phosphorylation
chemical_list: D002147:Calmodulin; D000205:Actomyosin; D000251:Adenosine Triphosphatases; D017301:Ca(2+) Mg(2+)-ATPase; D009218:Myosins