Phosphorylation of tropomyosin during development in mammalian striated muscle

Alpha-Tropomyosin from rat cardiac muscle was shown by two-dimensional gel electrophoresis to become phosphorylated when tissue slices were incubated in Eagle's medium supplemented with 32Pi. In the adult rat and mouse heart the level of phosphorylation was approximately 30% but the level was much higher in the foetal heart (60-70%). A similar developmental trend was observed in skeletal muscle from the rat and mouse, where phosphorylated forms of both alpha- and beta-tropomyosins were observed. When rat cardiac cells were grown in tissue culture in the presence of 32Pi, radioactivity was incorporated into the region of the gel containing tropomyosin.