Fig. 4: RTN4IP1 is required for CoQ synthesis.
From: Mitochondrial matrix RTN4IP1/OPA10 is an oxidoreductase for coenzyme Q synthesis
a, Volcano plot of MTS-TurboID (left) versus RTN4IP1-TurboID (right) biotinylated proteins (Supplementary Data 6). Statistical significance against FC revealed significantly different proteins between MTS-TurboID-labeled and RTN4IP1-TurboID-labeled samples. A total of 32 proteins were significantly biotinylated by RTN4IP1-TurboID (RTN4IP1 interactome) (P < 0.05, FC > 2). The proteins clustered by each function are highlighted. See Extended Data Fig. 6b for details. b, Normalized mass signal intensities of the top 20 biotinylated proteins labeled by RTN4IP1-TurboID among the 32 significantly biotinylated proteins. c,d, LC–PRM analysis of RTN4IP1-assisted O-methyltransferase activity of COQ3 using DMeQ2 as a substrate. All samples were incubated with S-adenosyl-methionine (SAM). The measured conversion ratio (that is (CoQ2)/(DMeQ2 and CoQ2)) is shown (n = 6 independent experiments): cofactor test (c) and mutant test (d). e, Proposed scheme for the O-methylation conversion of DMeQ2 to CoQ2 with COQ3/RTN4IP1. f–h, Histograms of LC–PRM measurement results for endogenous CoQs (f) and de novo-synthesized heavy CoQs (g) from heavy 4-HB (13C6) treatment in various C2C12 cells: Rtn4ip1-knockout (KO) cells (f), RTN4IP1-OE C2C12 cells (g) and Rtn4ip1-knockout (KO) and RTN4IP1-rescued C2C12 cells (h) (n = 3 biological replicates). The y axis is the normalized mass intensity unit per the sample’s protein mass; representative samples are shown. All precursor ions were cationized and detected as a form of ammonium adduct (NH4+) of the respective CoQ9 and CoQ9H2 molecules. Mean values are shown with error bars representing the standard deviation. Statistical significance was determined using a two-tailed Student’s t-test: *P < 0.05, **P < 0.01, ***P < 0.001; NS, not significant. Source data can be found in the Source Data file. Ctrl, Control.
