CPSF plays a key role in pre-mRNA 3'-end formation, recognizing the AAUAAA signal sequence and interacting with poly(A)polymerase and other factors to bring about cleavage and poly(A) addition. This subunit is involved in the RNA recognition step of the polyadenylation reaction (By similarity). CPSF is a heterotetramer composed of four distinct subunits 160 (cpsf-1), 100 (cpsf-2), 70 (cpsf-3), and 30 kDa (cpsf-4). Belongs to the CPSF1 family.