The function of Ensembl gene identifier ENSG00000121350 (PYROXD1, pyridine nucleotide-disulphide oxidoreductase domain 1) is as follows. Flavoprotein whose role is to protect RTCB, the catalytic subunit of the tRNA ligase complex (tRNA-LC) involved in tRNA splicing and unfolded protein response, from oxidative inactivation (PubMed:33930333). It directly binds and shields the catalytic center of RTCB, prior to guanylylation, when it is inactive and its active site is vulnerable to oxidation under aerobic conditions. The interaction of PYROXD1 with RTCB is allosterically regulated by NAD(P)H binding and reduction of its FAD cofactor, while reoxidation of PYROXD1 thanks to its NADPH dehydrogenase activity triggers the timed release of RTCB, enabling its subsequent activation. Thereby, this protective mechanism may also function as a molecular timer, regulating RTCB activation through controlled release (PubMed:40069351). .