Term Name:	mRNA guanylyltransferase activity
Synonyms:	GTP--RNA guanylyltransferase activity, GTP:mRNA guanylyltransferase activity, messenger RNA guanylyltransferase activity, mRNA capping enzyme activity, protein lambda2
Definition:	Catalysis of the reaction: GTP + (5')pp-Pur-mRNA = diphosphate + G(5')ppp-Pur-mRNA; G(5')ppp-Pur-mRNA is mRNA containing a guanosine residue linked 5' through three phosphates to the 5' position of the terminal residue.
Ontology:	GO: Molecular Function [GO:0004484]    QuickGO    AmiGO