RNA guanine-7 methyltransferase activating subunit (RAMAC)

The **RNA guanine-7 methyltransferase activating subunit (RAMAC)**, also known as **RNMT-activating miniprotein (RAM)**, is a small, highly conserved protein that functions as an allosteric activator of RNA guanine-7 methyltransferase (RNMT) in vertebrates[1][2][5][6][10]. This complex is essential for the methylation of the 7-methylguanosine cap at the 5' end of mRNAs, a critical modification required for mRNA stability, efficient translation, and protection from exonucleases. RAMAC itself is not catalytically active but binds to RNMT and stabilizes structural regions required for enzymatic activity, optimizing substrate recognition and methyl group transfer[1][2][6]. Loss or inhibition of RAMAC impairs mRNA cap formation, with widespread effects on gene expression and cellular viability. RAMAC is not currently considered a direct therapeutic target, but the RNMT-RAMAC complex is being studied as a vulnerability in cancer, particularly PIK3CA-mutant breast cancer, where cap methylation machinery may play a regulatory role[10].

Other names

RNA guanine-N7 methyltransferase activating subunitRNMT-activating miniproteinRAMFAM103A1C15orf18RAMMETProtein FAM103A1RNMT-activating mRNA cap methyltransferase subunitRNMT-activating mini proteinprotein FAM103A1HsT19360MGC2560

Not applicable; RAMAC is a protein cofactor, not a direct drug target; mechanistic actions relate to allosteric activation of RNMT