Molecular model of METTL6 (purple) complexed with serine tRNA (red) and serine-tRNA ligase (beige and green). METTL6 (methyltransferase 6) is an enzyme that specifically modifies transfer RNA (tRNA) molecules through a process called methylation. Serine tRNA is specifically designed to carry the amino acid serine and deliver it to the growing protein chain during translation based on the instructions encoded in the mRNA. Serine-tRNA ligase acts as a molecular matchmaker between the amino acid serine and its corresponding tRNA molecules.