IMMUNOHISTOCHEMISTRY: CALDESMON

CALDESMON IS A SMOOTH MUSCLE AND NON-MUSCLE REGULATORY PROTEIN THAT INTERACTS WITH ACTIN, MYOSIN, TROPOMYOSIN, AND CALMODULIN. SMOOTH MUSCLE CALDESMON IS AN ELONGATED MOLECULE WITH A CALMODULIN, TROPOMYOSIN, AND ACTION-BINDING REGION AT THE C-TERMINUS AND A MYOSIN BINDING DOMAIN AT THE N-TERMINUS. 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. CALDESMON IS A USEFUL MARKER FOR SMOOTH MUSCLE TUMORS.