Catalytic subunit of the mRNA-capping methyltransferase RNMT:RAMAC complex that methylates the N7 position of the added guanosine to the 5′-cap structure of mRNAs (PubMed:10347220, PubMed:11114884, PubMed:22099306, PubMed:27422871, PubMed:9705270, PubMed:9790902). Binds RNA containing 5′-terminal GpppC (PubMed:11114884).
