title: Role of myosin in the stimulatory effect of caldesmon on the interaction between actin, myosin, and ATP.
abstract: We have previously shown that caldesmon at low concentrations stimulates the interaction between actin, myosin, and ATP, while at high concentrations it inhibits the interaction [Ishikawa, R., Okagaki, T., Higashi-Fujime, S., & Kohama, K. (1991) J. Biol. Chem. 266, 21784-21790]. When the effect of caldesmon at low concentrations was monitored by measuring myosin ATPase activity in the absence of actin, the effect was slightly but significantly stimulatory; and at higher concentrations no inhibitory effect was observed. Therefore, we related the stimulatory effect with the myosin-binding property of caldesmon. In the presence of actin, a low concentration of caldesmon was not enough to evince the stimulatory effect: myosin concentration must also be low. This is because the stimulatory effect was obscured when myosin concentration was elevated. Ca(2+)-calmodulin abolished the stimulatory effect of caldesmon. However, the concentration of calmodulin required to abolish the stimulation was higher than that required to abolish the inhibition.
authors.affiliation: Department of Pharmacology, Gunma University School of Medicine.
authors.forename: Y
authors.initials: Y
authors.lastname: Lin
authors.forename: R
authors.initials: R
authors.lastname: Ishikawa
authors.forename: K
authors.initials: K
authors.lastname: Kohama
mesh_terms: D000199:Actins / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000378:metabolism*; D000818:Animals; D002147:Calmodulin / Q000494:pharmacology; D002148:Calmodulin-Binding Proteins / Q000378:metabolism / Q000494:pharmacology*; D002645:Chickens; D006868:Hydrolysis; D009130:Muscle, Smooth / Q000378:metabolism; D009132:Muscles / Q000378:metabolism; D009218:Myosins / Q000378:metabolism*
chemical_list: D000199:Actins; D002147:Calmodulin; D002148:Calmodulin-Binding Proteins; D000255:Adenosine Triphosphate; D009218:Myosins