[Quantitative distribution and partial identification of actin-like protein in rat liver mitochondria].

A comparative study of the primary structure of a mitochondrial polypeptide (Mr = 42000), using a peptide mapping technique, has demonstrated its similarity to actin, especially to that isolated from smooth muscle. The actin-like protein content in liver mitochondria is 2%. The protein is readily removed from the organelles but remains tightly bound to the mitochondria after addition of the high molecular weight compound polyvinylpyrrolidone to the isolation medium. The data obtained are discussed in terms of conservative structure of the action molecule.