TROPOMODULIN FUNCTION AND THIN FILAMENT ASSEMBLY IN CARDIAC MYOCYTES

The regulation of thin filament length is a fundamental property of al l striated muscles. Tropomodulin is an actin and tropomyosin binding p rotein that is exclusively associated with the free (pointed) ends of thin filaments. In vitro and in vivo studies reveal that tropomodulin is an actin filament pointed end capping protein, which is required to maintain the final length of thin filaments and is essential for cont ractile activity in embryonic chick cardiac myocytes. Understanding th e mechanisms of thin filament assembly, as well as determining the rol es of proteins modulating actin filament dynamics, is important for fu ture considerations of the molecular bases for myopathies seen in vari ous types of heart disease.