Fig. 2: ROMO1 promotes reductive shift of the redox landscape of the mitochondrial cysteinome.

a–d Distributions of the averaged TG/WT activity-based protein profiling ratios of the mitochondrial cysteinome in the heart (a), liver (b), skeletal muscle (SKM) (c), and brain (d). Mitochondrial proteome was curated using MitoCarta 3.0. Blue, gray, and red dots indicate reduced (Log₂R_(TG/WT) ≥ 0.58), unchanged (-0.58<Log₂R_(TG/WT) < 0.58), and oxidized (Log₂R_(TG/WT) ≤ -0.58) cysteine sites in the TG mitochondria, respectively. Note that C15 and C42 were detected in the four tissues (highlighted). Inset pie charts show sub-mitochondrial distributions of the proteins with reduced cysteine residues. OMM, outer mitochondrial membrane; IMM, inner mitochondrial membrane. n = 3-4 independent biological replicates from 6-8 young mice (3-month-old) for each tissue (2 M 4 F for liver; 4 M 4 F for heart, SKM, and brain). e Numbers of cysteine sites with or without altered redox status in TG mice as shown in (a–d). f, g As in (a–d), except that the mitochondrial cysteinome redox changes were measured in the heart of cardiomyocyte-specific Romo1 knockout (cKO) mice (f) or in the liver of hepatocyte-specific Romo1 knockout (hKO) mice (g), along with their respective control groups. n = 4 independent biological replicates from 8 mice (4 M 4 F for each group). 3-month-old mice were used. Note that C15 and C42 of ROMO1 were detected in the cKO group. h Numbers of cysteine sites with or without altered redox status in KO mice as shown in (f, g). i Gene ontology analysis of the mitochondrial proteins with reduced and oxidized cysteines in the tissues of TG and KO mice, respectively. The top 5 hits in each tissue are shown. Source data are provided as a Source Data file.