The Localization of Carnitine Palmitoyltransferase on the Inner Membrane of Bovine Liver Mitochondria

Abstract

Abstract The inner membrane from rat and beef liver mitochondria was shown to provide a barrier to the passage of fatty acyl-CoA derivatives, as determined by the absence of reduction of flavoproteins associated with the acyl-CoA dehydrogenase and the electron transferring flavoprotein when palmitoyl-CoA was incubated with inner membrane mitochondrial particles in the absence of l-carnitine. Carnitine palmitoyl-transferase was observed to be present on both sides of the inner membrane but not on the outer mitochondrial membrane. Antibodies which inactivated carnitine palmitoyl-transferase I and carnitine palmitoyltransferase II were found to inhibit the carnitine palmitoyltransferase reaction on the external surfaces of the inner membrane, but only those antibodies which inactivated carnitine palmitoyltransferase II inhibited the carnitine palmitoyltransferase reaction on the internal surface of the inner membrane of beef liver mitochondria. Data are also presented showing that the flavoprotein reduced following the addition of acyl-l-carnitine or acyl-CoA plus l-carnitine is probably the acyl-CoA dehydrogenase and not the electron transferring protein.