Cell-type capping

RNAs are capped by a viral reaction similar to that in the cell. GTP is first covalently bound to GTase as GTase-GMP, which is then transferred to the processed ppRNA to form a GpppN RNA. The RNA is further N7-methylated and 2'O-methylated by two other viral enzymes.

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

Enzymatic reactions
RNA triphosphatase: Rhea 67004
Guanylyl transfer on viral RNA: Rhea 67012
N7 Methyltransferase: Rhea 67008
2'O Methyltransferase: Rhea 67020