InterPro domain: IPR006941

The major pathways of mRNA turnover in eukaryotes initiate with shortening of the poly(A) tail. CAF1 (also known as CCR4-associated factor 1) is an RNase of the DEDD superfamily, and a subunit of the CCR4-NOT complex that mediates 3' to 5' mRNA deadenylation [ 1 , 2 ]. In yeast, CAF1 ( P39008 ) is also known as POP2, and encodes a critical component of the major cytoplasmic deadenylase [ 3 , 4 ]. It is required for normal mRNA deadenylation in vivo and localises to the cytoplasm. CAF1 copurifies with a CCR4-dependent poly(A)-specific exonuclease activity. The crystal structure of Saccharomyces cerevisiae POP2 has been resolved [ 5 ].

Some members of this family contain a single-stranded nucleic acid binding domain, R3H, such as poly(A)-specific ribonuclease (PARN), which also contains an RRM domain [ 6 ]. PARN is only conserved in vertebrates and may be important in regulated deadenylation such as early developmentand DNA damage response [ 7 , 8 ].

1. A complex containing the CCR4 and CAF1 proteins is involved in mRNA deadenylation in Drosophila. EMBO J. 23, 2862-71
2. Conservation of the deadenylase activity of proteins of the Caf1 family in human. RNA 11, 487-94
3. The yeast POP2 gene encodes a nuclease involved in mRNA deadenylation. Nucleic Acids Res. 29, 2448-55
4. The transcription factor associated Ccr4 and Caf1 proteins are components of the major cytoplasmic mRNA deadenylase in Saccharomyces cerevisiae. Cell 104, 377-86
5. X-ray structure and activity of the yeast Pop2 protein: a nuclease subunit of the mRNA deadenylase complex. EMBO Rep. 4, 1150-5
6. Distinct roles of the R3H and RRM domains in poly(A)-specific ribonuclease structural integrity and catalysis. Biochim. Biophys. Acta 1834, 1089-98
7. mRNA deadenylation by PARN is essential for embryogenesis in higher plants. RNA 10, 1200-14
8. Nuclear deadenylation/polyadenylation factors regulate 3' processing in response to DNA damage. EMBO J. 29, 1674-87