CCR4-Not
Multiprotein complex used in gene expression From Wikipedia, the free encyclopedia
Multiprotein complex used in gene expression From Wikipedia, the free encyclopedia
Carbon Catabolite Repression—Negative On TATA-less, or CCR4-Not, is a multiprotein complex that functions in gene expression.[2][3] The complex has multiple enzymatic activities as both a poly(A) 3′-5′ exonuclease and a ubiquitin ligase.[4][5][6][7] The exonuclease activity of CCR4-Not shortens the poly(A) tail found at 3' end of almost every eukaryotic mRNA.[8] The complex is present both in the nucleus where it regulates transcription and in the cytoplasm where it associates with translating ribosomes and RNA processing bodies.[2][3] In mammalian cell, it has a function in the regulation of the cell cycle, chromatin modification, activation and inhibition of transcription initiation, control of transcription elongation, RNA export, nuclear RNA surveillance, and DNA damage repair in nucleus. Ccr4–Not complex plays an important role in mRNA decay and protein quality control in the cytoplasm.[9]
The human CCR4-Not complex is composed of structural (non-catalytic) subunits and those that have exonuclease and E3 ligase activity. Some but not all of the human subunits are conserved in budding yeast.[10] In yeast the complex has nine core subunits, comprising Ccr4 (carbon catabolite repression), Caf proteins (Ccr4 associated factor) (Caf1, Caf40, Caf130) and Not proteins (Not1, Not2, Not3, Not4, and Not5).[11]
| Subunit | MW (kDa)[A] | Key Features |
|---|---|---|
| CNOT1 | 267 | "Scaffold" with non-catalytic function. Linked to the maintenance of embryonic stem cells.[12] |
| CNOT2 | 60 | Structural component. Linked to the maintenance of embryonic stem cells.[12] |
| CNOT3 | 82 | Structural component. Linked to the maintenance of embryonic stem cells.[13][12] |
| CNOT4 | 64 | Active as E3 ubiquitin ligase.[7] |
| CNOT6 | 63 | 3′-5′ exonuclease with preference for polyadenylated mRNA substates.[5] Has a human paralog CNOT6L. |
| CNOT7 | 33 | 3′-5′ exonuclease that is partially redundant with CNOT8.[4] |
| CNOT8 | 34 | 3′-5′ exonuclease.[4] |
| CNOT9 | 34 | Serves a non-catalytic function.[14] |
| CNOT10 | 82 | Non-catalytic subunit that forms a module with CNOT11 that is absent in fungi.[15] |
| CNOT11 | 55 | Non-catalytic subunit that forms a module with CNOT10 that is absent in fungi.[15] |
A Molecular weight of human subunits from Uniprot.
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