Premium
Association of the mammalian proto‐oncoprotein Int‐6 with the three protein complexes eIF3, COP9 signalosome and 26S proteasome
Author(s) -
Hoareau Alves Karine,
Bochard Valérie,
Réty Stéphane,
Jalinot Pierre
Publication year - 2002
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(02)03147-2
Subject(s) - cop9 signalosome , proteasome , int , microbiology and biotechnology , biology , chemistry , biochemistry , protease , peptide hydrolases , computer science , enzyme , operating system
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.