(A,B) Spectrophotometric measurement of Cyt c oxidase (CIV; A) and NADH Cyt c reductase (CIII; B) activities in solubilized mitochondrial extracts. Mitochondria were isolated from cells expressing the wild type form of Cor1 (Cor1WT) or the mutant Cor1N63A, N187A, D192A, V189A, Y65A, L238A, K240A (Cor1**). 