FIGURE 1.
The mammalian CPA machinery consists of four multisubunit complexes and other auxiliary factors. Schematic showing the mammalian CPA machinery. It consists of CPSF, CstF, CFI and CFII. There are six CPSF subunits, CPSP160, CPSF100, CPSF73, CPSF30, FIP1, and WDR33. CPSF160, CPSF30, and WDR33 are involved in the recognition of the AAUAAA PAS, while CPSF100 and CPSF73 participate in endonucleolytic cleavage of the pre-mRNA. FIP1 facilitates the assembly of the polyadenylation and cleavage machinery. Two auxiliary factors, Symplekin and RBBP6, are also required for the cleavage reaction. Lightning bolt: endonucleolytic cleavage.
