N(epsilon)-GMP-L-lysyl-[protein] + a 5'-end diphospho-(purine-ribonucleoside) in mRNA + 2 H(+) <=> a 5'-end (5'-triphosphoguanosine)-(purine-ribonucleoside) in mRNA + L-lysyl-[protein]
n(epsilon)-gmp-l-lysyl-[protein] + a 5'-end diphospho-(purine-ribonucleoside) in mrna + 2 h(+) <=> a 5'-end (5'-triphosphoguanosine)-(purine-ribonucleoside) in mrna + l-lysyl-[protein]