title: Association of the mammalian proto-oncoprotein Int-6 with the three protein complexes eIF3, COP9 signalosome and 26S proteasome.
abstract: The mammalian Int-6 protein has been characterized as a subunit of the eIF3 translation initiation factor and also as a transforming protein when its C-terminal part is deleted. It includes a protein domain, which also exists in various subunits of eIF3, of the 26S proteasome and of the COP9 signalosome (CSN). By performing a two-hybrid screen with Int-6 as bait, we have isolated subunits belonging to all three complexes, namely eIF3-p110, Rpt4, CSN3 and CSN6. The results of transient expression experiments in COS7 cells confirmed the interaction of Int-6 with Rpt4, CSN3 and CSN6, but also showed that Int-6 is able to bind another subunit of the CSN: CSN7a. Immunoprecipitation experiments performed with the endogenous proteins showed that Int-6 binds the entire CSN, but in low amount, and also that Int-6 is associated with the 26S proteasome. Taken together these results show that the Int-6 protein can bind the three complexes with various efficiencies, possibly exerting a regulatory activity in both protein translation and degradation.
authors.affiliation: Laboratoire de Biologie Moléculaire et Cellulaire, UMR5665-Centre National de la Recherche Scientifique, Ecole Normale Supérieure de Lyon, 46, Allée d'Italie, 69364 Cedex 07, Lyon, France
authors.forename: Karine
authors.initials: K
authors.lastname: Hoareau Alves
authors.forename: Valérie
authors.initials: V
authors.lastname: Bochard
authors.forename: Stéphane
authors.initials: S
authors.lastname: Réty
authors.forename: Pierre
authors.initials: P
authors.lastname: Jalinot
mesh_terms: D000818:Animals; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D000075686:COP9 Signalosome Complex; D019556:COS Cells; D039621:Eukaryotic Initiation Factor-3 / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D019169:Jurkat Cells; D008322:Mammals; D010447:Peptide Hydrolases / Q000235:genetics / Q000378:metabolism*; D011233:Precipitin Tests; D046988:Proteasome Endopeptidase Complex; D021122:Protein Subunits
chemical_list: D029681:Arabidopsis Proteins; C445070:CSN6B protein, Arabidopsis; D039621:Eukaryotic Initiation Factor-3; D021122:Protein Subunits; D010447:Peptide Hydrolases; D000075686:COP9 Signalosome Complex; D046988:Proteasome Endopeptidase Complex; C061553:ATP dependent 26S protease