The enzyme from Saccharomyces cerevisiae is active only towards uridine38 and uridine39, and shows no activity with uridine40 (cf. EC 220.127.116.11, tRNA pseudouridine38-40 synthase) . In vitro the enzyme from mouse is active on uridine39 and very slightly on uridine38 (human tRNALeu) .
Lecointe, F., Simos, G., Sauer, A., Hurt, E.C., Motorin, Y. and Grosjean, H. Characterization of yeast protein Deg1 as pseudouridine synthase (Pus3) catalyzing the formation of Ψ38 and Ψ39 in tRNA anticodon loop. J. Biol. Chem.273 (1998) 1316–1323. [DOI] [PMID: 9430663]
Chen, J. and Patton, J.R. Pseudouridine synthase 3 from mouse modifies the anticodon loop of tRNA. Biochemistry39 (2000) 12723–12730. [DOI] [PMID: 11027153]