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Characterization of the mammalian RNA exonuclease 5/NEF-sp as a testis-specific nuclear 3′ → 5′ exoribonuclease

Type of publication Peer-reviewed
Publikationsform Original article (peer-reviewed)
Author Silva Sara, Homolka David, Pillai Ramesh S.,
Project Genome protection by germline small RNAs
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Original article (peer-reviewed)

Journal RNA
Volume (Issue) 23(9)
Page(s) 1385 - 1392
Title of proceedings RNA
DOI 10.1261/rna.060723.117

Open Access

Type of Open Access Publisher (Gold Open Access)


Ribonucleases catalyze maturation of functional RNAs or mediate degradation of cellular transcripts, activities that are critical for gene expression control. Here we identify a previously uncharacterized mammalian nuclease family member NEF-sp (RNA exonuclease 5 [REXO5] or LOC81691) as a testis-specific factor. Recombinant human NEF-sp demonstrates a divalent metal ion-dependent 3′ → 5′ exoribonuclease activity. This activity is specific to single-stranded RNA substrates and is independent of their length. The presence of a 2′-O-methyl modification at the 3′ end of the RNA substrate is inhibitory. Ectopically expressed NEF-sp localizes to the nucleolar/nuclear compartment in mammalian cell cultures and this is dependent on an amino-terminal nuclear localization signal. Finally, mice lacking NEF-sp are viable and display normal fertility, likely indicating overlapping functions with other nucleases. Taken together, our study provides the first biochemical and genetic exploration of the role of the NEF-sp exoribonuclease in the mammalian genome.