Caldesmon150 regulates the tropomyosin-enhanced actin-myosin interaction in gizzard smooth muscle.
Using a reconstituted system in which myosin was preferentially phosphorylated, we examined the regulatory action of caldesmon150 on the smooth muscle actin-myosin interaction. Caldesmon150 inhibited the tropomyosin-enhanced actomyosin ATPase activity in a Ca2+-independent manner. This inhibitory effect of caldesmon150 was observed to be overcome by the addition of calmodulin in a Ca2+-dependent manner. In accordance with the observations of ATPase activity, we demonstrated evidence that the regulatory action of caldesmon150 on the actin site was mainly through control of the tropomyosin-enhanced actin-myosin interaction and calmodulin confers the Ca2+-sensitivity upon the caldesmon150 action determined by the cosedimentation method.
D000199:Actins / Q000378:metabolism*; D000205:Actomyosin / Q000378:metabolism; D000818:Animals; D002118:Calcium / Q000494:pharmacology; D002148:Calmodulin-Binding Proteins / Q000494:pharmacology*; D002645:Chickens; D003864:Depression, Chemical; D005895:Gizzard, Avian; D009119:Muscle Contraction; D009130:Muscle, Smooth / Q000502:physiology*; D009218:Myosins / Q000378:metabolism*; D010766:Phosphorylation; D014335:Tropomyosin / Q000378:metabolism
D000199:Actins; D002148:Calmodulin-Binding Proteins; D014335:Tropomyosin; D000205:Actomyosin; D009218:Myosins; D002118:Calcium