Commentary: Effect of Skeletal Muscle Native Tropomyosin on the Interaction of Amoeba Actin with Heavy Meromyosin

Abstract

Keywords: troponin, tropomyosin, cardiomyopathy, troponin T, mutations Troponin-tropomyosin inhibits skeletal and cardiac muscle contraction at low Ca rigor-type myosin S1 to actin-tropomyosin-troponin, particularly at saturating Ca2+, produces activation of myosin ATPase activity in excess of that seen in the absence of the regulatory proteins. The binding energy of S1 can overcome the inhibitory activity of troponin (Bremel et al., 1972) and may allow tropomyosin to move deep into the groove of actin. That particular arrangement of actin, tropomyosin, and troponin is a much better activator of ATP hydrolysis than actin alone. That active configuration of actin was called state 2 in the Hill model (Hill et al., 1980) and later named the M state because of its requirement for tight myosin binding.