Molecular mechanisms of calcium regulation of striated muscle contraction and its genetic disorder

Abstract

Contraction of skeletal and cardiac muscles is regulated by Ca²⁺ through a specific Ca²⁺-receptive protein, troponin, regularly distributed along the thin filaments. This protein consists of three different subunits, troponins C, I and T. In this article, studies on the structural and biochemical aspects of the molecular mechanisms of Ca²⁺-regulation were first reviewed with particular reference to the regulatory role of troponin T. Several properties of the isoforms of troponin from fast and slow skeletal and cardiac muscles were discussed, based on the findings obtained by the use of troponin-exchange techniques under physiological conditions. Recent findings on the functional consequence of mutations in human cardiac troponins T and I found in familial hypertrophic cardiomyopathy were also presented. The results clarified the increase in Ca²⁺-sensitivity of contraction to be the critical consequence due to this genetic disorder.