The effect of cross‐innervation on the tropomyosin composition of rabbit skeletal muscle

Abstract
Soleus, semitendinosus and crureus muscles of the rabbit were found to contain α- and β-tropomyosin subunits and additional forms that have been provisionally designated γ and δ. Extensor digitorum longus and psoas muscles contained only α and β subunits, the relative proportions of which varied between single fibres of psoas muscle. On cross-innervation of rabbit soleus and extensor digitorum longus muscles, the fraction of the total tropomyosin present as the β subunit remained constant. The relative proportions of α, γ and δ subunits changed as would be expected from the change in speed that occurred.