Members of this family of proteins are part of the yeast nuclear pore complex-associated pre-60S ribosomal subunit [1]. The family functions as a highly conserved exonuclease that is required for the 5'-end maturation of 5.8S and 25S rRNAs, demonstrating that 5'-end processing also has a redundant pathway. Nop25 binds late pre-60S ribosomes, accompanying them from the nucleolus to the nuclear periphery; and there is evidence for both physical and functional links between late 60S subunit processing and export [2].

1: Molecular cloning and characterization of Nop25, a novel nucleolar RNA binding protein, highly conserved in vertebrate species. Suzuki S, Kanno M, Fujiwara T, Sugiyama H, Yokoyama A, Takahashi H, Tanaka J; Exp Cell Res. 2006;312:1031-1041. PMID:16430885

2: Rrp17p is a eukaryotic exonuclease required for 5' end processing of Pre-60S ribosomal RNA. Oeffinger M, Zenklusen D, Ferguson A, Wei KE, El Hage A, Tollervey D, Chait BT, Singer RH, Rout MP; Mol Cell. 2009;36:768-781. PMID:20005841