a 3'-end 3'-phospho-ribonucleotide-RNA + ATP <=> a 3'-end 2',3'-cyclophospho-ribonucleotide-RNA + AMP + diphosphate
a 3'-end 3'-phospho-ribonucleotide-rna + atp <=> a 3'-end 2',3'-cyclophospho-ribonucleotide-rna + amp + diphosphate