Fig 1: Arginine deprivation–induced aberrant mRNA translation at AGA codons is counteracted by METTL1 function. A, METTL1–WDR4–mediated m7G46 modification of tRNAArg (UCU) leads to increased tRNA stability. B, Immunoblot analysis for AKT and RPS6K activation after 48-hour ADI treatment in A375 and SK-MEL-28 cells. Total and phosphorylated forms of these proteins were imaged with different species primary antibodies and visualized in different fluorescent channels on the same membrane. Representative images shown from 2 biological replicates. C and D, GFP median fluorescence intensity (MFI) in A375 (C) and SK-MEL-28 (D) AGA+1 cells ectopically expressing METTL1 and/or WDR4. Ctrl, control. E and F, Effects of METTL1 S27 mutations on MFI in A375 AGA+1 (E) and SK-MEL-28 AGA+1 (F) cells. G, Violin plots showing the proportion of AGA codons in the transcripts corresponding to the proteins in the global proteome, the top 10% downregulated proteins, and top 10% upregulated proteins (48 hours). Median values are next to each violin. H, Violin plots showing the proportion of AGA codons in the transcripts corresponding to the global transcriptome, the top 10% downregulated transcripts, and top 10% upregulated transcripts (48 hours). Median values are indicated next to each violin. I, Representation of the top enriched GO terms in the top 10% downregulated proteins. Indicated P values as per the Fisher exact tests. C–F, Data are presented as the median ± SD of a representative experiment from 2 biological replicates. C and D, Statistical analysis was performed using ordinary one way ANOVA with Šidák multiple testing correction; E and F, ANOVA using Šidák multiple testing correction; G and H, Wilcoxon test using Holm-Bonferroni mulitple testing correction; a.u., arbitrary units; *, P < 0.033; **, P < 0.002; ***, P < 0.001.