This entry includes CPSF4/CPSF4L from humans and Yth1 from yeasts. Most members have several CCCH type zinc finger domains, which are responsible for the nucleotide recognition [, ]. In animals, the CPSF complex is the central complex of the cleavage and polyadenylation (CP) reaction. It carries the catalytic activity for pre-mRNA cleavage, and its interaction with the AAUAAA sequence is essential for cleavage and the AAUAAA dependence of polyadenylation []. It is composed of five subunits: CPSF160, CPSF100, CPSF73 and CPSF30 (also known as CPSF4) and Fip1. CPSF4 has been shown to bind RNA polymers with a preference for poly(U) [, , ]. In humans, CPSF4 has also been shown to interact with influenza A virus NS1 and block processing of pre-mRNAs, thereby preventing nuclear export of host cell mRNAs []. Two subcomplexes are required for both steps in pre-mRNA 3'-end processing in yeast, the cleavage factor I (CF I) and the Cleavage Polyadenylation Factor (CPF), which likewise consists of the cleavage factor II (CF II) and the polyadenylation factor I (PF I). Yth1, the CPSF4 homologue, is an RNA-binding component of the CPF complex. Yth1 interacts with the pre-mRNA and with other CPF subunits, Brr5/Ysh1 and the polyadenylation-specific Fip1 [, ].
