title: Macrophage myosin. Regulation of actin-activated ATPase, activity by phosphorylation of the 20,000-dalton light chain.
abstract: Myosin was purified from rabbit alveolar macrophages in a form that could not be activated by actin. This myosin could be phosphorylated by an endogenous myosin light chain kinase, up to 2 mol of phosphate being incorporated/mol of myosin. The site phosphorylated was located on the 20,000-dalton myosin light chain. Phosphorylation of macrophage myosin was found to be necessary for actin activation of myosin ATPase activity. Moreover, the actin-activated ATPase activity was found to vary directly with the extent of myosin phosphorylation, maximal phosphorylation (2 mol of Pi/mol of myosin) resulting in an actin-activated MgATPase activity of approximately 200 nmol of Pi/mg of myosin/min at 37 degrees C. These results establish that phosphyoyration of the 20,000-dalton light chain of myosin is sufficient to regulate the actin-activated ATPase activity of macrophage myosin.
mesh_terms: D000199:Actins / Q000378:metabolism*; D000205:Actomyosin / Q000302:isolation & purification / Q000378:metabolism; D000251:Adenosine Triphosphatases / Q000378:metabolism*; D000818:Animals; D004789:Enzyme Activation; D008264:Macrophages / Q000201:enzymology*; D008274:Magnesium / Q000494:pharmacology; D008970:Molecular Weight; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism*; D011817:Rabbits
chemical_list: D000199:Actins; D000205:Actomyosin; D011494:Protein Kinases; D000251:Adenosine Triphosphatases; D008274:Magnesium