Fig. 6. Br is required for complex III assembly and activity.

a Quantitative proteomic analysis of WT and br zKO isolated adult skeletal muscle (SKM) mitochondria. Mean values of log₂ fold change (zKO/WT) for each detected protein from three biological replicates are plotted in a volcano plot. Subunits of each of the ETC complexes are labeled in the indicated colors. CI–CV = Complex I–Complex IV. p-values from two-sided unpaired t-test. b The median log₂ fold change (zKO/WT) of all detected ETC proteins are further depicted in a dendrogram heatmap and separated by complex membership. AF = assembly factors. c The median log₂ fold change (zKO/WT) of CI–CIV proteins were superimposed onto the structures of human CI–CIV to visually depict the observed changes. The same scalebar from panel 6b applies. Undetected proteins are shown in gray. d SDS-PAGE of purified WT and zKO SKM mitochondria followed by immunoblotting for the indicated ETC proteins. Image is representative of two experiments. e Quantitation of SDS-PAGE in 6d. Data represent mean and SEM. n = 5, except for Uqcrc2 where n = 3. p-values from two-sided unpaired t-test. f BN-PAGE and western blot analysis of WT and zKO SKM mitochondria. Position of free III₂ (red) and III₂ + IV_n (black) supercomplexes are indicated by arrowheads. g Spectrophotometric respiratory chain activity assay (RCA) of WT and zKO SKM mitochondria. Data represent mean and SEM. Each dot represents one animal, n = 12 for WT and zKO animals. p-values from two-sided unpaired t-test.