YbaK/aminoacyl-tRNA synthetase-associated domain This domain of unknown function is found in numerous prokaryote organisms. The structure of YbaK shows a novel fold. This domain also occurs in a number of prolyl-tRNA synthetases (proRS) from prokaryotes. Thus, the domain is thought to be involved in oligonucleotide binding, with possible roles in recognition/discrimination or editing of prolyl-tRNA [<cite idref="PUB00010589"/>].