title: Influence of an actin-modulating protein from smooth muscle on actin-myosin interaction.
abstract: The actin-modulating protein from pig stomach smooth muscle (PSAM) which reduces the average filament length has two opposite effects on the interaction of actin with skeletal muscle myosin: (1) stimulation of both the Mg2+-ATPase activity and superprecipitation at low KCl concentrations, and (2) inhibition of these two interrelated processes at an ionic strength close to physiological. Both stimulation and inhibition were Ca2+-dependent, reflecting the requirement for Ca2+ for the interaction of the modulator with actin. With acto-subfragment-1, only inhibition of the actin-activated ATPase was observed. Possible implications of these effects for studies on the regulation of smooth muscle contraction are discussed.
mesh_terms: D000199:Actins / Q000378:metabolism*; D000205:Actomyosin / Q000378:metabolism*; D000818:Animals; D003598:Cytoskeletal Proteins; D003599:Cytoskeleton / Q000648:ultrastructure; D007700:Kinetics; D008854:Microscopy, Electron; D009130:Muscle, Smooth / Q000502:physiology*; D009132:Muscles / Q000378:metabolism; D009218:Myosins / Q000378:metabolism*; D011506:Proteins / Q000494:pharmacology*; D011817:Rabbits; D013270:Stomach / Q000502:physiology; D013552:Swine
chemical_list: D000199:Actins; D003598:Cytoskeletal Proteins; D011506:Proteins; C028514:actin-modulating proteins; D000205:Actomyosin; D009218:Myosins