Multiplicity of mitochondrial inner membrane antigens from beef heart reacting with antimitochondrial antibodies in sera of patients with primary biliary cirrhosis

Mitochondrial inner membrane proteins extracted from beef heart tissue were examined for reactivity to antimitochondrial antibody (AMA) present in sera of patients with primary biliary cirrhosis (PBC) by an immunoblotting technique. Four proteins, which reacted with AMA, had molecular weights of 70 kDa, 54 kDa, 51 kDa and 45 kDa, as defined by their RF in SDS-PAGE gel. There was no correlation between the number of specificities and the titers of AMA as determined by immunofluorescence analysis. The 70-kDa protein was dissociated into a 36-kDa protein by trypsin digestion which still reacted with AMA. The reactivity to AMA of the 54-, 51- and 45-kDa proteins was abolished by trypsin digestion.