Non-catalytic component of a methyltransferase complex required for the formation of N(7)-methylguanine in a subset of RNA species, such as tRNAs, mRNAs and microRNAs (miRNAs). In the methyltransferase complex, it is required to stabilize and induce conformational changes of the catalytic subunit. Required for the formation of N(7)-methylguanine at position 46 (m7G46) in tRNA. Also required for the formation of N(7)-methylguanine at internal sites in a subset of mRNAs. Also required for methylation of a specific subset of miRNAs, such as let-7. Independently of METTL1, also plays a role in genome stability: localizes at the DNA replication site and regulates endonucleolytic activities of FEN1.
