Fig. 1

Identification of METTL13 as an eEF1A-specific methyltransferase. a Workflow of mass spectrometry-based quantitative peptide pull-down screen. Synthetic peptides corresponding N-terminally trimethylated (Nt-Me3) and unmethylated (Nt-Me0) eEF1A were used as baits to enrich proteins from HAP-1 cell extracts. b Volcano plot demonstrating enrichment of proteins by the unmodified (cyan circles) versus N-terminally trimethylated (magenta circles) bait peptides. The curved line represents the significance cutoff (FDR = 0.01 and s0 = 0.1). The putative methyltransferase METTL13 is indicated and all represented proteins are listed in Supplementary Data 1. c Domain organization of METTL13. The boundaries for used constructs encompassing the N-terminal (MT13-N) and the C-terminal (MT13-C) methyltransferase domains are indicated. d, e Evaluation of METTL13 constructs for eEF1A-specific methyltransferase activity. MT13-N (d) and MT13-C (e) were incubated with [³H]-AdoMet and eEF1A1 carrying an N-terminal or C-terminal His-tag in the absence of cofactors and in the presence of either GDP or GTP. Methylation was visualized by fluorography (top panels) and the membranes were stained with Ponceau S (bottom panels) to assess protein loading