FIGURE 4.

Activity and abundance of the OXPHOS complexes and their subunits in oma1-1 mitochondria. (A) Immunodetection, Coomassie (CBB) staining and in-gel enzyme activity of mitochondrial respiratory chain complexes separated by blue-native polyacrylamide gel electrophoresis (BN-PAGE). Mitochondria were isolated from 14-day-old WT and oma1-1 plants grown under optimal conditions (LD, 22°C) or at elevated temperature (LD, 30°C). (B) Quantification of the activity and abundance of the analyzed complexes. The protein level of complexes I and V was quantified based on CBB staining and immunodetection with antibodies directed against selected subunits. The abundance of complex IV was quantified solely based on signal detection from antibody directed against COX2. In each experiment, values of relative activity and protein abundance were calculated as percentage of volume determined for wild-type plants (set to 100%). (C) Western blot analysis of the subunits of complex I, IV and V in isolated mitochondrial fraction using SDS-PAGE. Representative immunoblots are shown. Protein amount was quantified densitometrically and values are given as percentage of the value obtained for wild-type plants (set as 100%). Mean values ± SD from at least three independent experiments are shown. The two-tailed Student’s t-test was used to determine if the differences between wild-type and oma1-1 mutants are statistically significant.^∗p ≤ 0.05.