Dual methyltransferase that catalyzes methylation of elongation factor 1-alpha (EEF1A1 and EEF1A2) at two different positions, and is therefore involved in the regulation of mRNA translation (PubMed:30612740, PubMed:30143613). Via its C-terminus, methylates EEF1A1 and EEF1A2 at the N-terminal residue 'Gly-2' (PubMed:30143613). Via its N-terminus dimethylates EEF1A1 and EEF1A2 at residue 'Lys-55' (PubMed:30612740, PubMed:30143613). Has no activity towards core histones H2A, H2B, H3 and H4 (PubMed:30612740). Negatively regulates cell proliferation at G1/S transition via transcriptional suppression of cell cycle regulatory genes such as CDK4 and CDK6 (PubMed:26763933). L-lysyl-[protein] + S-adenosyl-L-methionine = H(+) + N(6)-methyl-L-lysyl-[protein] + S-adenosyl-L-homocysteine N(6)-methyl-L-lysyl-[protein] + S-adenosyl-L-methionine = H(+) + N(6),N(6)-dimethyl-L-lysyl-[protein] + S-adenosyl-L-homocysteine N-terminal glycyl-L-lysyl-L-glutamyl-[protein] + 3 S-adenosyl-L-methionine = 3 H(+) + N-terminal N,N,N-trimethyl-glycyl-L-lysyl-L-glutamyl-[protein] + 3 S-adenosyl-L-homocysteine Protein N-terminal methyltransferase activity is inhibited by GTP and GDP. Forms a tripartite complex containing GAB1, METTL13 and SPRY2 (PubMed:29408807). Within the complex interacts with GAB1 and SPRY2 (PubMed:29408807). Genetic variants in METTL13 define the deafness modifier locus DFNB26M [MIM:605429]. The DFNB26M phenotype is characterized by normal hearing despite the presence of homozygosity for a causative deafness mutation in the GAB1 gene. METTL13 unregulation may be involved in tumorigenesis. High METTL13 expression has been observed in pancreatic and lung cancer tissues, correlates with overexpression of dimethylated elongation factor 1-alpha and is associated with poor clinical outcome. The disease mechanism involves dysregulation of mRNA translation and enhanced protein synthesis to sustain growth of malignant cells. Present in the circulating blood plasma of cancer patients, particularly in ovarian and non-small cell lung cancer patients, may potentially be used as a biomarker (PubMed:27659353). Acts as a tumor suppressor in bladder cancer suppressing cell migration and invasion (PubMed:26763933). Reduced expression is seen in later stages of the disease (PubMed:26763933). Belongs to the methyltransferase superfamily. Extended N-terminus. Extended N-terminus.