CNOT6L plays a role in the deadenylation of mRNAs in the cytoplasm. Has 3'-5' poly(A) exoribonuclease activity for synthetic poly(A) RNA substrate. It may be involved in the deadenylation-dependent degradation of mRNAs through the 3'-UTR AU-rich element-mediated mechanism. Involved in deadenylation-dependent degradation of CDKN1B mRNA.