This is a family of endoribonucleases involved in RNA biosynthesis which has been named XendoU in Xenopus laevis. XendoU is a U-specific metal dependent enzyme that produces products with a 2'-3' cyclic phosphate termini.

1: The structure of the endoribonuclease XendoU: From small nucleolar RNA processing to severe acute respiratory syndrome coronavirus replication. Renzi F, Caffarelli E, Laneve P, Bozzoni I, Brunori M, Vallone B; Proc Natl Acad Sci U S A. 2006;103:12365-12370. PMID:16895992