Mus_musculusFamily: RNase_PH_C Number of Genes: 6
Ensembl IDSymbolEntrez IDRBD RBPome PRIExpresion PathwayPhenotype ParalogOrthologGO



This family includes 3'-5' exoribonucleases. Ribonuclease PH contains a single copy of this domain, and removes nucleotide residues following the -CCA terminus of tRNA. Polyribonucleotide nucleotidyltransferase (PNPase) contains two tandem copies of the domain. PNPase is involved in mRNA degradation in a 3'-5' direction. The exosome is a 3'-5' exoribonuclease complex that is required for 3' processing of the 5.8S rRNA. Three of its five protein components, P46948 Q12277 and P25359 contain a copy of this domain [1]. Q10205 a hypothetical protein from S. pombe appears to belong to an uncharacterised subfamily. This subfamily is found in both eukaryotes and archaebacteria.


The PH (phosphorolytic) domain is responsible for 3'-5' exoribonuclease activity, although in some proteins this domain has lost its catalytic function. An active PH domain uses inorganic phosphate as a nucleophile, adding it across the phosphodiester bond between the end two nucleotides in order to release ribonucleoside 5'-diphosphate (rNDP) from the 3' end of the RNA substrate.


  1. Mitchell P, Petfalski E, Shevchenko A, Mann M, Tollervey D; , Cell 1997;91:457-466.: The exosome: a conserved eukaryotic RNA processing complex containing multiple 3'-->5' exoribonucleases. PUBMED:9390555 EPMC:9390555.