Catalyzes the methylation of 5-carboxymethyl uridine to 5- methylcarboxymethyl uridine at the wobble position of the anticodon loop in tRNA via its methyltransferase domain (PubMed:20123966, PubMed:20308323, PubMed:31079898). Catalyzes the last step in the formation of 5-methylcarboxymethyl uridine at the wobble position of the anticodon loop in target tRNA (PubMed:20123966, PubMed:20308323). Has a preference for tRNA(Arg) and tRNA(Glu), and does not bind tRNA(Lys) (PubMed:20308323). Binds tRNA and catalyzes the iron and alpha-ketoglutarate dependent hydroxylation of 5-methylcarboxymethyl uridine at the wobble position of the anticodon loop in tRNA via its dioxygenase domain, giving rise to 5-(S)- methoxycarbonylhydroxymethyluridine; has a preference for tRNA(Gly) (PubMed:21285950). Required for normal survival after DNA damage (PubMed:20308323). May inhibit apoptosis and promote cell survival and angiogenesis (PubMed:19293182). {ECO:0000269|PubMed:19293182, ECO:0000269|PubMed:20123966, ECO:0000269|PubMed:20308323, ECO:0000269|PubMed:21285950, ECO:0000269|PubMed:31079898}. This is the function of ALKBH8 (alkB homolog 8, tRNA methyltransferase, Ensembl gene identifier ENSG00000137760).