Cleavage Stimulation Factor

A RNA-binding protein that stimulates the cleavage of the 3' end of MRNA near the POLYADENYLATION SITE. It is a heterotrimer of 55, 64 and 77 kD subunits and combines with CLEAVAGE STIMULATION FACTOR to form a stable complex with mRNA that directs the 3' cleavage and polyadenylation reaction.