Conservation of the deadenylase activity of proteins of the Caf1 family in human

The yeast Pop2 protein, belonging to the eukaryotic Caf1 family, is required for mRNA deadenylation in vivo. It also catalyzes poly(A) degradation in vitro, even though this property has been questioned. Caf1 proteins are related to RNase D, a feature supported by the recently published structure of Pop2. Yeast Pop2 contains, however, a divergent active site while its human homologs harbor consensus catalytic residues. Given these differences, we tested whether its deadenylase activity is conserved in the human homologs Caf1 and Pop2. Our data demonstrate that both human factors degrade poly(A) tails indicating their involvement in mRNA metabolism.