The human CCR4-NOT complex contains 7 core subunits: CNOT1, CNOT2, CNOT3, CNOT9/RCD1, CNOT10, TAB182, and C2ORF29. Complexes contain either CNOT7 or CNOT8 (with CNOT8-containing complexes apparently involved in nuclear RNA splicing and CNOT7-containing complexes involved in cytoplasmic mRNA decay) and CNOT6 or CNOT6L. CNOT6 and CNOT6L are catalytic exoribonucleases. CNOT7 and CNOT8 also have ribonuclease activity. CNOT1 is the largest subunit and, based on yeast two-hybrid assays, interacts with CNOT2, CNOT7, CNOT8, and CNOT9, thus acting as a scaffold.