PUS4, or TruB pseudouridine (psi) synthase family member 1, is a human gene encoded by TRUB1. It may also be known as: Probable tRNA pseudouridine synthase 1; Probable tRNA pseudouridine synthase 1 . The encoded protein is an enzyme with an amino acid length of 349 and a mass of 37.3 kDa. Other isoforms may exist. PUS4 is a member of the Pseudouridine synthase TruB family. Homologs of this gene exist in other organisms, including: Mouse, Rat, Zebrafish, Frog, Chicken.