Localization and Mode of Action of the Inhibitory Protein Component of the Troponin Complex

Abstract

It is now well established that the troponin complex consists of three distinct protein components that differ in molecular weight, amino acid composition, and function. A number of names for these components have been used by different investigators (Table 1), and in this article we shall use the terms inhibitory protein and calcium-binding protein to describe the proteins with inhibitory activity on the Mg++-stimulated ATPase of actomyosin and with a high affinity for calcium, respectively. In the absence of a clearly defined function for the third component of the troponin complex, it will be identified by its molecular weight and referred to as the 37,000 component.