Orientation of chargerin II (A6L) in the ATP synthase of rat liver mitochondria determined with antibodies against peptides of the protein

Abstract

Previous studies suggested that the hydrophobic protein chargerin II, which is encoded in the unidentified reading frame A6L of mitochondrial DNA (URFA6L), may have a key role in the energy transduction by mitochondrial ATP synthase because an antibody against chargerin II inhibited ATP synthesis and ATP-Pi exchange, in an energy-dependent fashion. In the present work, the orientation of chargerin II in F_o of the ATP synthase of rat liver mitochondria was examined using antibodies against peptides of chargerin II. Results showed that its N-terminal region (about 8 amino acid residues) was exposed on the surface of the C-side of F_o, but its C-terminal and charge-cluster regions were buried in F_o.