label: a 5'-end phospho (purine-ribonucleoside) in mRNA + N(2),N(2),N(7)-trimethyl-GDP + 2 H(+) => a 5'-end (N(2),N(2),N(7)-trimethyl 5'-triphosphoguanosine)-purine ribonucleoside in mRNA + H2O
label_lc: a 5'-end phospho (purine-ribonucleoside) in mrna + n(2),n(2),n(7)-trimethyl-gdp + 2 h(+) => a 5'-end (n(2),n(2),n(7)-trimethyl 5'-triphosphoguanosine)-purine ribonucleoside in mrna + h2o