Has 3'-5' poly(A) exoribonuclease activity for synthetic poly(A) RNA substrate. Its function seems to be partially redundant with that of CNOT7. Catalytic component of the CCR4-NOT complex which is linked to various cellular processes including bulk mRNA degradation, miRNA-mediated repression, translational repression during translational initiation and general transcription regulation. During miRNA-mediated repression the complex seems also to act as translational repressor during translational initiation. Additional complex functions may be a consequence of its influence on mRNA expression. Associates with members of the BTG family such as TOB1 and BTG2 and is required for their anti-proliferative activity. Exonucleolytic cleavage of poly(A) to 5'-AMP. Component of the CCR4-NOT complex; distinct complexes seem to exist that differ in the participation of probably mutually exclusive catalytic subunits; the complex contains two deadenylase subunits, CNOT6 or CNOT6L, and CNOT7 or CNOT8. In the complex interacts directly with CNOT1. Interacts with BTG1, BTG2 and TOB1 (By similarity). Interacts with BTG4 (PubMed:27065194). Expressed in embryonic stem (ES) cells. Belongs to the CAF1 family.