CPEB, or cytoplasmic polyadenylation element binding protein, is a highly conserved RNA-binding protein that promotes the elongation of the polyadenine tail of messenger RNA. CPEB is present at postsynaptic sites and dendrites where it stimulates polyadenylation and translation in response to synaptic activity. CPEB most commonly activates the target RNA for translation, but can also act as a repressor, dependent on its phosphorylation state. As a repressor, CPEB interacts with the deadenylation complex and shortens the polyadenine tail of mRNAs. In animals, CPEB is expressed in several alternative splicing isoforms that are specific to particular tissues and functions, including the self-cleaving Mammalian CPEB3 ribozyme. CPEB was first identified in Xenopus oocytes and associated with meiosis; a role has also been identified in the spermatogenesis of Caenorhabditis elegans.
The cytoplasmic polyadenylation element (CPE) is a sequence element found in the 3' untranslated region of messenger RNA. While several sequence elements are known to regulate cytoplasmic polyadenylation, CPE is the best characterized. The most common CPE sequence is UUUUAU, though there are other variations. Binding of CPE binding protein to this region promotes the extension of the existing polyadenine tail and, in general, activation of the mRNA for protein translation. This elongation occurs after the mRNA has been exported from the nucleus to the cytoplasm. A longer poly(A) tail attracts more cytoplasmic polyadenine binding proteins (PABPs) which interact with several other cytoplasmic proteins that encourage the mRNA and the ribosome to associate. The lengthening of the poly(A) tail thus has a role in increasing translational efficiency of the mRNA. The polyadenine tails are extended from approximately 40 bases to 150 bases.
Cleavage and polyadenylation specificity factor subunit 5 (CPSF5) is an enzyme that in humans is encoded by the NUDT21 gene. It belongs to the Nudix family of hydrolases.
Cold shock domain-containing protein E1 is a protein that in humans is encoded by the CSDE1 gene.
Cleavage and polyadenylation specificity factor subunit 2 is a protein that in humans is encoded by the CPSF2 gene. This protein is a subunit of the cleavage and polyadenylation specificity factor (CPSF) complex which plays a key role in pre-mRNA 3' end processing and polyadenylation. The CPSF2 protein connects the two subunits of the complex, mCF and mPSF. Its structure contributes both to the stability of the subunits interaction and to the flexibility of the complex necessary for function. This protein has been identified as an essential subunit of the complex as certain mutations in the region inhibit CPSF complex formation.
DNA-binding protein A is a protein that in humans is encoded by the CSDA gene.
Symplekin is a protein that in humans is encoded by the SYMPK gene.
Cleavage stimulation factor 64 kDa subunit, tau variant is a protein that in humans is encoded by the CSTF2T gene.
60S ribosomal protein L36 is a protein that in humans is encoded by the RPL36 gene.
Cleavage and polyadenylation specificity factor subunit 3 is a protein that in humans is encoded by the CPSF3 gene.
60S ribosomal protein L24 is a protein that in humans is encoded by the RPL24 gene.
60S ribosomal protein L36a is a protein that in humans is encoded by the RPL36A gene.
Dynein light chain roadblock-type 1 is a protein that in humans is encoded by the DYNLRB1 gene.
60S ribosomal protein L8 is a protein that in humans is encoded by the RPL8 gene.
Cleavage and polyadenylation specificity factor subunit 4 is a protein that in humans is encoded by the CPSF4 gene.
Eukaryotic translation initiation factor 4E transporter is a protein that in humans is encoded by the EIF4ENIF1 gene.
Integrator complex subunit 11 is a protein that in humans is encoded by the CPSF3L gene.
Zinc finger protein 346 is a protein that in humans is encoded by the ZNF346 gene.
Prolactin regulatory element-binding protein is a protein that in humans is encoded by the PREB gene.
High mobility group nucleosome-binding domain-containing protein 4 is a transcription factor that in humans is encoded by the HMGN4 gene.
