Fig. 6

Biological experiments Mitochondrial proteins from wild type (wt) and mutant cells expressing Qcr2-HA were purified. Proteins were resolved on 12% SDS–PAGE followed by immunoblotting with antibodies against Cob, Cyt1 and HA. See list of mutants in Table 2. Panel a Accumulation of bc1 subunits: Cyt1, Qcr2 and Cob, in the wild type and in Δcyt1, Δcor1 and Δcpb3. In absence of the translation factor Cbp3, Cob is absent. Panel b Mitochondria were solubilised in 1% digitonine and immunoprecipitated with HA coupled agarose beads. The different fractions were analyzed. T: Total mitochondrial proteins; S: supernatant; W: wash; IP: immunoprecipitate. na: not applicable. Qcr2 is subjected to some degradation in absence of Cor1 unless the presence of a cocktail of anti-proteases. Panel c Model for the first step of the assembly of complex III