Calmodulin-binding proteins and calcium/calmodulin-regulated enzyme activities associated with brain actomyosin.
Calcium- and calmodulin-regulated ATPase and protein kinase activities are shown to be strongly associated with brain actomyosin. Similar enzymatic activities and an invariable polypeptide profile on sodium dodecyl sulfate-polyacrylamide gel electrophoresis were obtained for brain actomyosin taken through a solubilization-precipitation cycle (1.0-0.1 M KCl), or precipitated from buffers containing 1% Triton X-100 or 10 mM EDTA and 10 mM EGTA. These data suggest a specific complex of brain actomyosin with a protein kinase similar to calmodulin-dependent kinase II, a 190-kDa calmodulin-binding protein (P190), and a calmodulin-like polypeptide. P190 was the major substrate for endogenous calcium-dependent phosphorylation. 125I-Calmodulin overlay technique revealed four major calmodulin-binding polypeptides associated with brain actomyosin: 50- and 60-kDa subunits of the calmodulin-dependent kinase II, P190, and a high molecular weight polypeptide which is probably fodrin. A fraction enriched in P190 had Ca2(+)- and calmodulin-stimulated MgATPase activity, but not myosin-like K-EDTA ATPase activity. The lack of immunological cross-reactivity between brain myosin heavy chain and P190 confirmed that they are distinct molecules.
Larson
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Department of Biochemistry, Faculdade de Medicina de Ribeirao Preto, Universidade de Sao Paulo, Brazil.
Espindola
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Espreafico
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D000205:Actomyosin / Q000378:metabolism*; D000251:Adenosine Triphosphatases / Q000378:metabolism; D000818:Animals; D001921:Brain / Q000201:enzymology*; D001923:Brain Chemistry; D002118:Calcium / Q000502:physiology*; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D002147:Calmodulin / Q000502:physiology*; D002148:Calmodulin-Binding Proteins / Q000276:immunology / Q000378:metabolism*; D003429:Cross Reactions; D004492:Edetic Acid / Q000032:analysis; D009218:Myosins / Q000276:immunology; D009419:Nerve Tissue Proteins / Q000378:metabolism; D010455:Peptides / Q000378:metabolism; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism; D011817:Rabbits; D051381:Rats
D002147:Calmodulin; D002148:Calmodulin-Binding Proteins; D009419:Nerve Tissue Proteins; D010455:Peptides; D000205:Actomyosin; D004492:Edetic Acid; D011494:Protein Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D000251:Adenosine Triphosphatases; D009218:Myosins; D002118:Calcium