Figure 4: COX7RP promotes assembly of respiratory chain supercomplexes.

Mitochondrial proteins of skeletal muscle from WT (a,c) and Cox7rpKO mice (b,d) were solubilized with digitonin in the concentration of 2 g g⁻¹ protein (a,b) or 0.5 g g⁻¹ protein (c,d), and subjected to blue native polyacrylamide gel electrophoresis (BN-PAGE) followed by second-dimensional SDS–PAGE. Western blot analysis was performed with antibodies for NDUFA9 of complex I, UQCRC2 of complex III, RISP of complex III, COX4 of complex IV and COX7RP. Positions corresponding to mitochondrial supercomplex species I/III₂/IV_n, I/III₂, III₂/IV_n, dimerized complex IV (IV₂) and monomerized complex IV (IV) are indicated. Percentages of UQCRC2, RISP or COX4 signal intensities in each whole amount are indicated in the images.