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