Caldesmon.
Caldesmon is a protein that is found in smooth muscle and in non-muscle cells. Two isoform classes produced by alternative splicing of one gene have been characterized. The smooth muscle, high molecular weight (89-93 kDa), caldesmon isoforms are exclusively found in adult and fully differentiated smooth muscle cells. The non-muscle, low molecular weight (59-63 kDa), caldesmon isoforms are found in non-muscle and in de-differentiated smooth muscle cells. The conserved regions of all isoforms contain caldesmon's properties such as binding to actin, tropomyosin, Ca(2+)-calmodulin, myosin and phospholipids. All isoforms are also very potent inhibitors of the actin-tropomyosin activated myosin MgATPase. Non-muscle and smooth muscle isoforms of caldesmon perform different roles in vivo. This may be reflected by the distinct cellular distribution of these isoform classes. Non-muscle caldesmon is a regulatory factor in the microfilament network and is thus involved in the assembly and stabilization of microfilaments. Smooth muscle caldesmon together with tropomyosin is a mediating factor for Ca(2+)-dependent inhibition of smooth muscle contraction.
Huber
P A
PA
Cardiac Medicine, Imperial College School of Medicine at the National Heart and Lung Institute, London, U.K.
D000818:Animals; D002148:Calmodulin-Binding Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000378:metabolism / Q000502:physiology; D006801:Humans; D009119:Muscle Contraction; D009124:Muscle Proteins / Q000378:metabolism; D009130:Muscle, Smooth / Q000737:chemistry / Q000502:physiology
D002148:Calmodulin-Binding Proteins; D009124:Muscle Proteins