Caldesmon/CALD1 Proteins and Enzymes

Caldesmon is a smooth muscle and nonmuscle regulatory protein that interacts with actin, myosin, tropomyosin, and calmodulin (1,2). Smooth muscle caldesmon is an elongated molecule with a calmodulin, tropomyosin, and actin-binding region at the C-terminus and a myosin-binding domain at the N-terminus (3). 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 reduced by calcium-calmodulin and is promoted by tropomyosin (4).