Cleavage factor

Cleavage factors are two closely related proteins involved in the cleavage of the 3' signaling region from a newly synthesized pre-messenger RNA (mRNA) molecule in the process of gene transcription. The cleavage is the first step in adding a polyadenine tail to the pre-mRNA, which is one of the necessary post-transcriptional modifications necessary for producing a mature mRNA. There are two cleavage factors involved in the assembly of the protein complex that mediates this process, CFI and CFII. They are recruited to the cleavage site by cleavage and polyadenylation specificity factor and cleavage stimulatory factor, and form a complex that also includes polyadenine polymerase, which performs the polyadenylation reaction.