FIGURE 2.

Mouse fibroblasts with disrupted cyt c (somatic and testis) alleles are OXPHOS-deficient. A, control (LF), cyt c dKO (L3, L4, and L7), wild-type cyt c cDNA reintroduced (CL1 and CL15), and mutant cyt c cDNA reintroduced (CL18) intact cells were analyzed for KCN-sensitive oxygen consumption. All cell lines were also analyzed for the ratio of the ascorbate-TMPD respiration (where electrons are donated directly to cyt c) to endogenous respiration (starting at complexes I and II). cyt c dKO cells and those reintroduced with the mutant cyt c cDNA did not respire. B and D, respiratory complexes (III and IV) activities measured by spectrophotometric assays. Citrate synthase activity was measured in all the samples (C) as a measure of mitochondrial levels. cyt c dKO cells and those reintroduced with the W60S mutant cyt c cDNA (CL18 and CL25) lacked complex IV and had reduced complex III activities.