Acts as catalytic component of the CCR4-NOT core complex, which in the nucleus seems to be a general transcription factor, and in the cytoplasm the major mRNA deadenylase involved in mRNA turnover (By similarity). Transcriptional regulator of circadian rhythms with poly(A)-degrading activity that affects the expression and rhythmicity of the clock core oscillator genes TOC1 and CCA1 (PubMed:26619288). Deadenylation may be a mechanism involved in the regulation of the circadian clock (PubMed:26619288). May play a negative role in response against oxidative stress (PubMed:26619288). Possesses magnesium-dependent poly(A)-specific exoribonuclease activity in vitro and is almost inactive with poly(U), poly(C) and poly(G) as substrates (PubMed:26619288). Exonucleolytic cleavage of poly(A) to 5'-AMP. Optimum pH is 6.5. Optimum temperature is 25 degrees Celsius. Component of the CCR4-NOT complex, at least composed of CRR4 and CAF1 proteins (By similarity). Forms homooligomers (PubMed:26619288). Expressed with a high amplitude circadian rhythm showing a peak in the late day, just before night. No visible phenotype under normal growth conditions. Plants overexpressing CCR4-4 exhibit retarded growth phenotype and severe reduction in root length that is attenuated over time. May be due to intron retention. May be due to intron retention. Belongs to the CCR4/nocturin family. Sequencing errors.