Component of the eukaryotic translation initiation factor 3 (eIF-3) complex, which is involved in protein synthesis of a specialized repertoire of mRNAs and, together with other initiation factors, stimulates binding of mRNA and methionyl-tRNAi to the 40S ribosome. The eIF-3 complex specifically targets and initiates translation of a subset of mRNAs involved in cell proliferation. Component of the COP9 signalosome complex (CSN), a complex involved in various cellular and developmental processes. The CSN complex is an essential regulator of the ubiquitin (Ubl) conjugation pathway by mediating the deneddylation of the cullin subunits of the SCF-type E3 ligase complexes, leading to decrease the Ubl ligase activity of SCF. The CSN complex plays an essential role in embryogenesis and oogenesis and is required to regulate microtubule stability in the early embryo. Mediates mei-1 targeting for degradation at the meiosis to mitosis transition via deneddylation of cul-3. Component of the eukaryotic translation initiation factor 3 (eIF-3) complex. Within the eIF-3 complex, interacts directly with eif-3.F. Component of the CSN complex, composed of csn-1, csn-2, csn-3, csn-4, csn-5, csn-6 and csn-7. Within the CSN complex, interacts directly with csn-1 and csn-4. Belongs to the eIF-3 subunit M family.