title: Isolation and properties of platelet myosin light chain kinase.
abstract: A protein kinase which phosphorylates the 20 000-dalton light chain of platelet myosin has been isolated from human blood platelets and purified approximately 600-fold. Elution of a 7.5% polyacrylamide gel following electrophoresis of the partially purified enzyme yielded a single peak of kinase activity which could be aligned with a protein band on  a stained gel. Assuming a globular shape, a native molecular weight of 83 000 (+/- 10%) was determined by gel filtration on Bio-Gel P-200. The kinase requires Mg2+ for activity and is not sensitive to the removal of trace Ca2+. The enzyme purified from human platelets phosphorylates the 20 000-dalton light chain of mouse fibroblast and chicken gizzard myosin, but does not phosphorylate human skeletal and cardiac myosin.
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism; D001792:Blood Platelets / Q000201:enzymology*; D004789:Enzyme Activation / Q000187:drug effects; D006801:Humans; D007700:Kinetics; D046911:Macromolecular Substances; D008274:Magnesium / Q000494:pharmacology; D008970:Molecular Weight; D009218:Myosins / Q000097:blood / Q000302:isolation & purification / Q000378:metabolism*; D011494:Protein Kinases / Q000097:blood* / Q000302:isolation & purification / Q000378:metabolism
chemical_list: D046911:Macromolecular Substances; D011494:Protein Kinases; D000251:Adenosine Triphosphatases; D009218:Myosins; D008274:Magnesium