This is the N-terminal domain found in archeal type-2 serine-tRNA ligase (SerRS) (EC:6.1.1.11). The SerRS N-terminal domain interacts with the extra-arm stem and the outer corner of tRNA specific to Selenocysteine (tRNA-Sec) [1, 2].

1: Tertiary structure of bacterial selenocysteine tRNA. Itoh Y, Sekine S, Suetsugu S, Yokoyama S; Nucleic Acids Res. 2013;41:6729-6738. PMID:23649835

2: Structure of the unusual seryl-tRNA synthetase reveals a distinct zinc-dependent mode of substrate recognition. Bilokapic S, Maier T, Ahel D, Gruic-Sovulj I, Soll D, Weygand-Durasevic I, Ban N; EMBO J. 2006;25:2498-2509. PMID:16675947