title: Phosphorylation of smooth muscle myosin light chain kinase by the catalytic subunit of adenosine 3': 5'-monophosphate-dependent protein kinase.
abstract: Turkey gizzard smooth muscle light chain kinase was purified by affinity chromatography on calcium dependent regulator weight of 125,000 +/- 5,000 in sodium dodecyl sulfate-polyacrylamide gel electrophoresis. When myosin light chain kinase is incubated with the catalytic subunit of cyclic AMP-dependent protein kinase, 1 mol of phosphate is incorporated per mol of myosin kinase. Brief tryptic digestion of the 32P-labeled myosin kinase liberates a single radioactive peptide with a molecular weight of approximately 22,000. Phosphorylation of myosin kinase results in a 2-fold decrease in the rate at which the enzyme phosphorylates the 20,000-dalton light chain of smooth muscle myosin. These results suggest that cyclic AMP has a direct effect on actin-myosin interaction in smooth muscle.
mesh_terms: D000818:Animals; D000242:Cyclic AMP / Q000494:pharmacology*; D004789:Enzyme Activation; D000070559:Gizzard, Non-avian / Q000201:enzymology*; D007700:Kinetics; D008970:Molecular Weight; D009132:Muscles / Q000201:enzymology*; D009218:Myosins; D010446:Peptide Fragments / Q000032:analysis; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism*
chemical_list: D010446:Peptide Fragments; D000242:Cyclic AMP; D011494:Protein Kinases; D009218:Myosins