Purification of a troponin I‐like factor from pig platelet

Abstract
A troponin I‐like factor has been purified from pig platelet by G150 Sephadex filtration of a low ionic strength extract, acidification at pH 4.2, ion exchange on DE‐52 cellulose, and affinity chromatography on calmodulin‐Sepharose. This protein (M r 17000), together with pig brain calmodulin and platelet tropomyosin, is able to participate to the reconstitution in vitro of a thin filament‐like complex which modulates with 55% calcium sensitivity 1 the platelet actin‐activated Mg2+‐dependent ATPase activity of rabbit skeletal muscle myosin.