Ca-inhibitory myosins: their structure and function.
Actin-myosin-ATPase interaction of Physarum is under inhibitory Ca-control. Ca-binding to myosin inhibits the interaction, while Ca-release from myosin removes inhibition. However, this myosin-linked control system alone is not sufficient to account for in vivo contraction. A Ca-dependent inhibitory factor, whose active principle appears to be identical with or similar to Ca-Lc of myosin, augments myosin-linked control by interacting with actin. This novel regulatory system may not be specific for the actomyosin system in Physarum plasmodia, because some actomyosin-related processes, i.e., secretion and motility, are subject to inhibitory Ca-control. Accumulation of examples for the inhibitory Ca-control in higher and lower eukaryotes will clarify its phylogenic significance.
Kohama
K
K
Department of Pharmacology, Faculty of Medicine, University of Tokyo, Japan.
D000199:Actins / Q000378:metabolism; D000251:Adenosine Triphosphatases / Q000037:antagonists & inhibitors / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D002118:Calcium / Q000378:metabolism / Q000502:physiology*; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D009218:Myosins / Q000032:analysis / Q000037:antagonists & inhibitors / Q000378:metabolism / Q000502:physiology*; D010766:Phosphorylation; D010804:Physarum / Q000502:physiology*
D000199:Actins; D000251:Adenosine Triphosphatases; D009218:Myosins; D002118:Calcium