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 (By similarity). Can bind oligonucleotides, such as poly-G, poly-C or poly-T (in vitro), but the physiological relevance of this is not certain. Does not bind poly-A. Enhances ligand-dependent transcriptional activity of nuclear hormone receptors, including RARA, expect ESR1-mediated transcription that is not only slightly increased, if at all. Homodimer. Component of the CCR4-NOT complex; distinct complexes seem to exist that differ in the participation of probably mutually exclusive catalytic subunits. Interacts with MYB, ATF2, RARA, RARB, RARG, RXRA, RXRB and RXRG. Identified in a complex with ATF2 bound to target DNA (By similarity). Interacts with NANOS2 (By similarity). Directly interacts with ZNF335. NANOS2 promotes its localization to P-body. Detected in spleen, thymus, prostate, testis, ovary and intestine. Belongs to the CNOT9 family. Extended N-terminus.