3'-5' exoribonuclease 1; 3'-5' exonuclease ERI1; Eri-1 homolog; histone mRNA 3'-end-specific exoribonuclease; histone mRNA 3'-exonuclease 1; protein 3'hexo; HEXO (ERI1, 3'EXO, THEX1)
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Function
- RNA exonuclease that binds to the 3'-end of histone mRNAs & degrades them, suggesting that it plays a role in histone mRNA decay after replication.
- a 2' & 3'-hydroxyl group at the last nucleotide of the histone 3'-end is required for efficient degradation of RNA substrates
- also able to degrade the 3'-overhangs of short interfering RNAs (siRNAs) in vitro, suggesting a possible role as regulator of RNA interference (RNAi)
- requires for binding the 5'-ACCCA-3' sequence present in stem-loop structure
- able to bind other mRNAs
- required for 5.8S rRNA 3'-end processing
- also binds to 5.8s ribosomal RNA
- binds with high affinity to the stem-loop structure of replication-dependent histone pre-mRNAs
- although it can bind simultaneously with SLBP to the 3'-end of histone mRNA, the presence of SLBP prevents the exonuclease activity
- identified in a histone pre-mRNA complex, at least composed of ERI1, LSM11, SLBP, SNRPB, SYNCRIP & YBX1
- interacts in a cooperative manner with SLBP to the mature 3'-end of histone mRNAs (putative)
- binds to 40S & 60S ribosomal subunits & to 80S assembled ribosomes
- found in a ternary complex with SLBP & the stem-loop structure of the 3'-end of histone mRNAs
- binds 2 Mg+2 per subunit
Structure
- the SAP domain is necessary for binding to the stem-loop structure of histone mRNAs & to form the ternary complex with SLBP, but not for 3'-end histone mRNA exonuclease activity
- contains 1 exonuclease domain
- contains 1 SAP domain