Component of the CCR4-NOT complex which is one of the major cellular mRNA deadenylases and is linked to various cellular processes including bulk mRNA degradation, miRNA-mediated repression, translational repression during translational initiation and general transcription regulation. Additional complex functions may be a consequence of its influence on mRNA expression. Involved in down-regulation of MYB- and JUN-dependent transcription. May play a role in cell differentiation. Required for retinoic acid-induced differentiation of F9 teratocarcinoma cells. Does not bind DNA by itself. Enhances ligand-dependent transcriptional activity of nuclear hormone receptors. May play a role in cell differentiation.