Blue native polyacrylamide gel electrophoresis (BN-PAGE) or colorless native polyacrylamide gel electrophoresis (CN-PAGE) allowed separation of the oxidative phosphorylation complexes of yeast mitochondria. These complexes were characterized by specific staining related to their enzymatic activity. Solubilization of mitochondria by different nonionic detergents such as Triton X-100, dodecyl maltoside, Nonidet P-40, Lubrol, octyl glucoside, or Hecameg led to the separation of F1-FO ATPase complexes exhibiting distinct apparent molecular masses related to different contaminating proteins and lipids. All these different forms were active in ATP hydrolysis as revealed directly on the gel. Analysis of the subunit composition of these complexes was carried out by a two-dimensional Tricine-SDS-PAGE and showed that the purest F1-FO ATPase complex was obtained with Lubrol, whereas with Hecameg and octyl glucoside, only the F1 part of ATPase was solubilized.