YbaK-like. The YbaK family of deacylase domains includes the INS amino acid-editing domain of the bacterial class II prolyl tRNA synthetase (ProRS), and it's trans-acting homologs, YbaK, ProX, and PrdX. The primary function of INS is to hydrolyze mischarged cysteinyl-tRNA(Pro)'s, thus helping ensure the fidelity of translation. Organisms whose ProRS lacks the INS domain express an INS homolog in trans (e.g. YbaK, ProX, or PrdX).