This domain is found in prokaryotic methionyl-tRNA synthetases, prokaryotic phenylalanyl tRNA synthetases the yeast GU4 nucleic-binding protein (G4p1 or p42, ARC1) [2], human tyrosyl-tRNA synthetase [1], and endothelial-monocyte activating polypeptide II. G4p1 binds specifically to tRNA form a complex with methionyl-tRNA synthetases [2]. In human tyrosyl-tRNA synthetase this domain may direct tRNA to the active site of the enzyme [2]. This domain may perform a common function in tRNA aminoacylation [1].

1: Human tyrosyl-tRNA synthetase shares amino acid sequence homology with a putative cytokine. Kleeman TA, Wei D, Simpson KL, First EA; J Biol Chem 1997;272:14420-14425. PMID:9162081

2: The yeast protein Arc1p binds to tRNA and functions as a cofactor for the methionyl-and glutamyl-tRNA synthetases. Simos G, Segref A, Fasiolo F, Hellmuth K, Shevchenko A, Mann M, Hurt EC; EMBO J 1996;15:5437-5448. PMID:8895587