Caldesmon is an actin- and myosin-binding protein implicated in the regulation of actomyosin interactions in smooth muscle and nonmuscle cells. Caldesmon stimulates actin binding of tropomyosin which increases the stabilization of actin filament structure. In muscle tissues, caldesmon inhibits the actomyosin ATPase by binding to F-actin. This inhibition is attenuated by calcium-calmodulin and is potentiated by tropomyosin. Caldesmon Iinteracts with actin,Mouse,yosin, two molecules of tropomyosin and with calmodulin. Caldesmon also plays an essential role during cellular mitosis and receptor capping.