Abstract
The topographical distribution of caldesmon (a calmodulin-binding, F-actin-interacting protein) and of actin was investigated in various organs of rats such as esophagus, intestine, submandibular gland, pancreas, adrenal gland, ovary, uterus, oviduct, kidney, skeletal muscle, heart, and aorta by means of light microscopic immunohistochemistry.
Positive immunostaining for caldesmon was observed in smooth muscle cells of all the organs examined, and myoepithelial cells of the submandibular gland. In addition, caldesmon was also present in the apical cytoplasm of the epithelial cells of the intestine, uterus, oviduct, submandibular gland, and pancreas and renal tubules, and in the peripheral cytoplasm of adrenal medullary cells.
The distribution of actin in these tissues shows almost the same pattern as that of caldesmon, though caldesmon was not detected in skeletal and cardiac muscles.
It is concluded that caldesmon is generally present not only in smooth muscle cells but also in non-muscle cells of various organs. This result suggests that the calmodulin-binding protein, caldesmon, may play an important role in the control of actin-myosin interaction of these cells.
