Figure 3.

YBEY is essential for mitochondrial gene expression. (A) Western blot analysis of select respiratory chain subunits from YBEY KO cells shows selective depletion of the mtDNA-encoded COX2 protein and of the nucleus-encoded NDUFB8 subunit. (All shown proteins, except COX2, are nucleus-encoded; VDAC1 and GAPDH are shown as loading controls.) (B) Metabolic [³⁵S]-methionine labelling of mitochondrial translation products reveals a nearly complete shutdown of protein synthesis in YBEY KO mitochondria. (C) Volcano plot summarizing the gene expression changes between YBEY⁺ and YBEY KO mitochondria as assessed by RNA-Seq. Select loci, further discussed in the text, are highlighted. See also Supplementary Table S5. (D) RT-qPCR measurement of select mitochondrial RNAs in YBEY⁺ and YBEY KO cells. Means ± SEM for n = 3 are shown; P-values, two-tailed t-test.