1. Service de Bioénergétique, CEA-Saclay, 91191 Gif-sur-Yvette Cedex, France, UMR 6191 CNRS-CEA-Aix-Marseille II, DEVM-CEA-Cadarache, 13108 St Paul lez Durance, France, and Department of Biochemistry, School of Medical Sciences, University of Bristol, University Walk, Bristol, BS8 1TD, United Kingdom