Myosin light-chain phosphatase.
1. A method for the isolation of a new enzyme, myosin light-chain phosphatase, from rabbit white skeletal muscle by using a Sepharose-phosphorylated myosin light-chain affinity column is described. 2. The enzyme migrated as a single component on electrophoresis in sodium dodecyl sulphate/polyacrylamide gel at pH7.0, with apparent mol.wt. 70000. 3. The enzyme was highly specific for the phosphorylated P-light chain of myosin, had pH optima at 6.5 and 8.0 and was not inhibited by NaF. 4. A Ca2+-sensitive 'ATPase' (adenosine triphosphatase) system consisting of myosin light-chain kinase, myosin light-chain phosphatase and the P-light chain is described. 5. Evidence is presented for a phosphoryl exchange between Pi, phosphorylated P-light chain and myosin light-chain phosphatase. 6. Heavy meromyosin prepared by chymotryptic digestion can be phosphorylated by myosin light-chain kinase. 7. The ATPase activities of myosin and heavy meromyosin, in the presence and absence of F-actin, were not significantly changed (+/- 10%) by phosphorylation of the P-light chain.
D000199:Actins; D000205:Actomyosin; D000818:Animals; D008274:Magnesium; D008970:Molecular Weight; D009132:Muscles / Q000201:enzymology; D015879:Myosin Subfragments; D009218:Myosins; D010710:Phosphates / Q000378:metabolism; D010750:Phosphoproteins; D010744:Phosphoric Monoester Hydrolases / Q000302:isolation & purification*; D011494:Protein Kinases / Q000302:isolation & purification; D011817:Rabbits
D000199:Actins; D015879:Myosin Subfragments; D010710:Phosphates; D010750:Phosphoproteins; D000205:Actomyosin; D011494:Protein Kinases; D010744:Phosphoric Monoester Hydrolases; D009218:Myosins; D008274:Magnesium