Biopolymers and cell. 1995; 11 (5): 28 - 36

CALDESMON IS A Ca2+-REGULATORY PROTEIN COMPONENT OF NATIVE AORTA SMOOTH MUSCLE FILAMENTS

V. M. Danilova, N. V. Kulikova, V. S. Tregubov, V. S. Omelyanuk, A, M. Filenko

The techniques of preparation and purification of calmodulin- and actin-binding protein caldesmon (CaD) from pig aorta smooth muscle is described. It is established that CaD prevents the interaction of myosin and actin thus inhibiting the Mg2+-ATPase activity of actomyosin irrespectively of Ca2+ concentration. The inhibitory effect of CaD is cancelled at addition of calmodulin in the presence of Ca2+. With the help of spectro-fluorimetry it is shown that calmodulin may bind to caldesmon causing conformational changes in its structure. Both the results obtained and the data known from literature suggest CaD to be a likely regulator of vascular smooth muscle actomyosin system.