selenocysteine tRNA tRNA Sec opal suppressor Trnau1 Trsp|opal suppressor|selenocysteine tRNA|Trnau1|tRNA Sec http://identifiers.org/mgd/MGI:4414022 nuclear encoded tRNA selenocysteine 2 (anticodon TCA) + O Gene tRNA gene n-TUtca2 genetic mapping MGI:4414022 Trsp