Cleavage and polyadenylation specificity factor

The pre-mRNA must undergo post-transcriptional modifications, forming mature RNA (mRNA), before they can be transported into the cytoplasm for translation into proteins.

The post-transcriptional modifications are: the addition of a 5' m7G cap, splicing of intronic sequences, and 3' cleavage and polyadenylation.

[3] It is the first protein to bind to the signaling region near the cleavage site of the pre-mRNA, to which the poly(A) tail will be added by polynucleotide adenylyltransferase.

The AAUAAA region is usually defined by a cytosine/adenine (CA) dinucleotide, which is the preferred sequence, that is 5' to the site of the endonucleolytic cleavage.

It catalyzes the cleavage reaction by recognizing the histone mRNA 3' processing site.

[4][5] CPSF-73 is a zinc-dependent hydrolase which cleaves the mRNA precursor between a CA dinucleotide just downstream the polyadenylation signal sequence AAUAAA.

[2] CPSF-160 (160 kDa) is the largest subunit of CPSF and directly binds to the AAUAAA polyadenylation signal.

WDR33 and CPSF-30 recognize the polyadenylation signal (PAS) in pre-mRNA, which aids in defining the position of RNA cleavage.

[4][5][9][10] Although CPSF-160 is the largest subunit of CPSF, a study conducted by Schönemann et al., debate that WDR33 is responsible for recognizing the PAS and not CPSF-160 as previously believed.

The study concluded that the reason that CPSF-160 was believed to be responsible for recognizing the PAS was due to the fact that the WDR33 subunit had not been discovered at the time of the claim.

It binds to RNA sequences upstream of the AAUAAA hexamer region in vitro.

Alternative polyadenylation (APA) is a regulatory mechanism that forms multiple 3' end on mRNA.