This entry represents the eukaryotic translation initiation factor 3 subunit M (eIF3m) and the COP9/Signalosome and eIF3 complex-shared subunit 1 (CIF-1) from roundworms. eIF3m is a component of the eukaryotic translation initiation factor 3 (eIF-3) complex, which is involved in protein synthesis and, together with other initiation factors, stimulates binding of mRNA and methionyl-tRNAi to the 40S ribosome []. In Caenorhabditis elegans, CIF-1 is a component of both the eIF3 and the COP9 signalosome (CSN) complexes. It regulates protein synthesis through the eIF3 complex and regulates the activity of cullin-RING E3-ubiquitin ligases (CRLs) through the CSN complex [, ]. CIF-1 appears to be the only ortholog of Csn7 encoded by the C. elegans genome [].
This entry includes eIF3m and COPS7A/B. eIF3m is a component of the eukaryotic translation initiation factor 3 (eIF-3) complex, which is involved in protein synthesis and, together with other initiation factors, stimulates binding of mRNA and methionyl-tRNAi to the 40S ribosome []. The COP9 signalosome (CSN) is a conserved protein complex that regulates the ubiquitin (Ubl) conjugation pathway by mediating the deneddylation of the cullin subunits of SCF-type E3 ligase complexes [], which leads to a decrease in Ubl ligase activity of SCF-type complexes such as SCF, CSA or DDB2 []. Protein kinases CK2 and D, which phosphorylate proteins such as cJun and p53 resulting in their degradation by the ubiquitin-26S proteasome system, also binds to CSN [, ]. The mammalian CSN typically consistis of eight subunits designated CSN1-CSN8. The fission yeast possesses a smaller version of the CSN, consisting only of six subunits, whereas a more distant CSN-like complex has been described in Saccharomyces cerevisiae [].
