EXOSC3

This gene encodes a non-catalytic component of the human exosome, a complex with 3'-5' exoribonuclease activity that plays a role in numerous RNA processing and degradation activities. Related pseudogenes of this gene are found on chromosome 19 and 21. Alternatively spliced transcript variants encoding different isoforms have been described. [provided by RefSeq, Jun 2012]

Full Name

exosome component 3

Research Area

Non-catalytic component of the RNA exosome complex which has 3'->5' exoribonuclease activity and participates in a multitude of cellular RNA processing and degradation events. In the nucleus, the RNA exosome complex is involved in proper maturation of stable RNA species such as rRNA, snRNA and snoRNA, in the elimination of RNA processing by-products and non-coding 'pervasive' transcripts, such as antisense RNA species and promoter-upstream transcripts (PROMPTs), and of mRNAs with processing defects, thereby limiting or excluding their export to the cytoplasm. The RNA exosome may be involved in Ig class switch recombination (CSR) and/or Ig variable region somatic hypermutation (SHM) by targeting AICDA deamination activity to transcribed dsDNA substrates. In the cytoplasm, the RNA exosome complex is involved in general mRNA turnover and specifically degrades inherently unstable mRNAs containing AU-rich elements (AREs) within their 3' untranslated regions, and in RNA surveillance pathways, preventing translation of aberrant mRNAs. It seems to be involved in degradation of histone mRNA. The catalytic inactive RNA exosome core complex of 9 subunits (Exo-9) is proposed to play a pivotal role in the binding and presentation of RNA for ribonucleolysis, and to serve as a scaffold for the association with catalytic subunits and accessory proteins or complexes. EXOSC3 as peripheral part of the Exo-9 complex stabilizes the hexameric ring of RNase PH-domain subunits through contacts with EXOSC9 and EXOSC5.

Biological Process

CUT catabolic process Source: UniProtKB
DNA deamination Source: UniProtKB
Exonucleolytic catabolism of deadenylated mRNA Source: UniProtKB
Exonucleolytic trimming to generate mature 3'-end of 5.8S rRNA from tricistronic rRNA transcript (SSU-rRNA, 5.8S rRNA, LSU-rRNA) Source: GO_Central
Isotype switching Source: UniProtKB
Nuclear polyadenylation-dependent rRNA catabolic process Source: GO_Central
Nuclear polyadenylation-dependent tRNA catabolic process Source: GO_Central
Nuclear retention of pre-mRNA with aberrant 3'-ends at the site of transcription Source: GO_Central
Nuclear-transcribed mRNA catabolic process, exonucleolytic, 3'-5' Source: GO_Central
Polyadenylation-dependent snoRNA 3'-end processing Source: GO_Central
Positive regulation of isotype switching Source: Ensembl
rRNA processing Source: UniProtKB
U4 snRNA 3'-end processing Source: GO_Central

Cellular Location

Nucleolus; Nucleus; Cytoplasm

Involvement in disease

Pontocerebellar hypoplasia 1B (PCH1B):
A severe autosomal recessive neurologic disorder characterized by a combination of cerebellar and spinal motor neuron degeneration beginning at birth. There is diffuse muscle weakness, progressive microcephaly, global developmental delay, and brainstem involvement.