TRMT1L is a tRNA methyltransferase that shapes the cytosolic tRNA modification landscape and, through it, global translation and stress resilience (PMID:39786990, PMID:39786998, PMID:39416027). It catalyzes N2,N2-dimethylguanosine (m2,2G): at position 26 of a subset of tRNA-Ala(AGC) isodecoders (PMID:33499731) and, distinct from the related TRMT1 activity, at position 27 of tyrosine tRNAs (PMID:39786990, PMID:39786998). Beyond direct methylation, TRMT1L is required for deposition of acp3U and dihyduridine on select tRNAs (tRNA-Tyr-GUA, tRNA-Cys-GCA, tRNA-Ala-CGC) through a circuit that can be uncoupled from its methyltransferase activity, placing it within a broader tRNA-modification network (PMID:39786990, PMID:39786998, PMID:39416027). Loss of TRMT1L reduces tRNA-Tyr-GUA levels, lowers global mRNA translation rates, and renders cells hypersensitive to oxidative stress (PMID:39786998, PMID:39416027). Consistent with a role in ribosome and tRNA biology, TRMT1L interacts with a component of the Rix1 ribosome biogenesis complex and binds 28S rRNA and a subset of tRNAs (PMID:39786998, PMID:39416027). In neurons, TRMT1L relocalizes from nucleoli to nuclear puncta specifically upon neuronal activation but not heat shock (PMID:33499731), and disruption of its mouse ortholog produces altered motor coordination and exploratory behavior with expression in neural tissues (PMID:17198746), linking the enzyme to neuronal function.