InterPro: IPR005009 Poxvirus mRNA capping enzyme, small subunit

Vaccinia virus, the prototypic poxvirus, possesses a double-stranded DNA genome of 191,686 base pairs capable of encoding approximately 200 proteins. Virion enzymes produce mature viral mRNA with eukaryotic features, including a 5' cap and a 3' poly(A) tail. V. virus mRNA capping enzyme is a multifunctional protein with RNA triphosphatase, RNA guanylyltransferase, RNA (guanine-7) methyltransferase, and transcription termination factor activities. The protein is a heterodimer of 95kDa and 33kDa subunits encoded by the v.virus D1 and D12 genes, respectively. The capping reaction entails transfer of GMP from GTP to the 5'-diphosphate end of mRNA via a covalent enzyme-(lysyl-GMP) intermediate.