The evolutionarily conserved CCR4-NOT complex is involved in several aspects of mRNA metabolism, including repression and activation of mRNA initiation, control of mRNA elongation, and the deadenylation and subsequent degradation of mRNA. In Saccharomyces the CCR4-NOT complex comprises a core complex of 9 proteins (Ccr4p, Caf1p, Caf40p, Caf130p, Not1p, Not2p, Not3p, Not4p, and Not5p), Caf4p, Caf16p, and several less well characterized proteins.