Ca2+-calmodulin-dependent regulation of F-actin-myelin basic protein interaction.
Myelin basic proteins (MBP) interacts with F-actin resulting in the precipitation of a complex of both proteins. Electron microscope observations of this complex reveal the presence of ordered bundles of F-actin filaments similar to those obtained from F-actin and troponin I. In addition to the bundles, there also appear short fragments of F-actin filaments. In the presence of Ca2+ calmodulin causes a release of MBP from its complex with F-actin, accompanied by dissociation of F-actin bundles into separate filaments. Parallel to the binding of MBP to F-actin the ATPase activity of actomyosin is progressively reduced. This inhibition is reversed by calmodulin but only in the presence of Ca2+. Studies of the binding of S-1 to F-actin and to the F-actin-MBP complex indicate that the interaction sites for MBP and S-1 on the actin molecule are different.
D000199:Actins / Q000378:metabolism*; D000205:Actomyosin / Q000378:metabolism; D000251:Adenosine Triphosphatases / Q000378:metabolism; D000818:Animals; D001921:Brain / Q000378:metabolism; D002118:Calcium / Q000494:pharmacology*; D002147:Calmodulin / Q000494:pharmacology*; D002417:Cattle; D007700:Kinetics; D046911:Macromolecular Substances; D008854:Microscopy, Electron; D004676:Myelin Basic Protein / Q000378:metabolism*; D014336:Troponin / Q000378:metabolism; D019210:Troponin I
D000199:Actins; D002147:Calmodulin; D046911:Macromolecular Substances; D004676:Myelin Basic Protein; D014336:Troponin; D019210:Troponin I; D000205:Actomyosin; D000251:Adenosine Triphosphatases; D002118:Calcium