Alphavirus -type capping

RNAs are capped by a unique viral reaction. GTP is first modified and covalently linked to the GTase as m7GMP, which is then transferred to the processed ppRNA to form a m7G-cap. The alphavirus GTase and the guanine-N7 MTase activities are located on the same protein. .

(RNA TPase=RNA triphosphatase, GTase=guanylyltransferase, MTase=methyltransferase, SAM= S-adenosylmethionine, SAH= S-adenosylhomocysteine)

Enzymatic reactions:
RNA triphosphatase: Rhea 67004
GTP N7methyltransferase: Rhea 46948 >Pfam
GTase-m7GMP: Rhea 54793
Guanylyl transfer: Rhea 54801
2'O Mtase reaction: Rhea 67020