Cleavage factors are two closely related protein

Protein

Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...

s involved in the cleavage of the 3' signaling region from a newly synthesized pre-messenger RNA

Messenger RNA

Messenger RNA is a molecule of RNA encoding a chemical "blueprint" for a protein product. mRNA is transcribed from a DNA template, and carries coding information to the sites of protein synthesis: the ribosomes. Here, the nucleic acid polymer is translated into a polymer of amino acids: a protein...

 (mRNA) molecule in the process of gene transcription

Transcription (genetics)

Transcription is the process of creating a complementary RNA copy of a sequence of DNA. Both RNA and DNA are nucleic acids, which use base pairs of nucleotides as a complementary language that can be converted back and forth from DNA to RNA by the action of the correct enzymes...

. The cleavage is the first step in adding a polyadenine tail

Polyadenylation

Polyadenylation is the addition of a poly tail to an RNA molecule. The poly tail consists of multiple adenosine monophosphates; in other words, it is a stretch of RNA that has only adenine bases. In eukaryotes, polyadenylation is part of the process that produces mature messenger RNA for translation...

 to the pre-mRNA, which is one of the necessary post-transcriptional modification

Post-transcriptional modification

Post-transcriptional modification is a process in cell biology by which, in eukaryotic cells, primary transcript RNA is converted into mature RNA. A notable example is the conversion of precursor messenger RNA into mature messenger RNA , which includes splicing and occurs prior to protein synthesis...

s necessary for producing a mature mRNA. There are two cleavage factors involved in the assembly of the protein complex

Protein complex

A multiprotein complex is a group of two or more associated polypeptide chains. If the different polypeptide chains contain different protein domain, the resulting multiprotein complex can have multiple catalytic functions...

 that mediates this process, CFI and CFII. They are recruited to the cleavage site by cleavage and polyadenylation specificity factor

Cleavage and polyadenylation specificity factor

Cleavage and polyadenylation specificity factor is involved in the cleavage of the 3' signaling region from a newly synthesized pre-messenger RNA molecule in the process of gene transcription...

 and cleavage stimulatory factor

Cleavage stimulatory factor

Cleavage stimulatory factor or cleavage stimulation factor is a heterotrimeric protein of about 200 kilodaltons that is involved in the cleavage of the 3' signaling region from a newly synthesized pre-messenger RNA molecule...

, and form a complex that also includes polyadenine polymerase, which performs the polyadenylation reaction.