preferred_name: a tRNA with a 3' CCA end + 3 diphosphate => a tRNA precursor + 2 CTP + ATP
preferred_name_lc: a trna with a 3' cca end + 3 diphosphate => a trna precursor + 2 ctp + atp
label: a tRNA with a 3' CCA end + 3 diphosphate => a tRNA precursor + 2 CTP + ATP
label_lc: a trna with a 3' cca end + 3 diphosphate => a trna precursor + 2 ctp + atp