title: Arabidopsis eIF3e (INT-6) associates with both eIF3c and the COP9 signalosome subunit CSN7.
abstract: The Arabidopsis COP9 signalosome is a multisubunit repressor of photomorphogenesis that is conserved among eukaryotes. This complex may have a general role in development. As a step in dissecting the biochemical mode of action of the COP9 signalosome, we determined the sequence of proteins that copurify with this complex. Here we describe the association between components of the COP9 signalosome (CSN1, CSN7, and CSN8) and two subunits of eukaryotic translation initiation factor 3 (eIF3), eIF3e (p48, known also as INT-6) and eIF3c (p105). To obtain a biochemical marker for Arabidopsis eIF3, we cloned the Arabidopsis ortholog of the eIF3 subunit eIF3b (PRT1). eIF3e coimmunoprecipitated with CSN7, and eIF3c coimmunoprecipitated with eIF3e, eIF3b, CSN8, and CSN1. eIF3e directly interacted with CSN7 and eIF3c. However, eIF3e and eIF3b cofractionated by gel filtration chromatography in a complex that was larger than the COP9 signalosome. Whereas eIF3, as detected through eIF3b, localized solely to the cytoplasm, eIF3e, like CSN7, was also found in the nucleus. This suggests that eIF3e and eIF3c are probably components of multiple complexes and that eIF3e and eIF3c associate with subunits of the COP9 signalosome, even though they are not components of the COP9 signalosome core complex. This interaction may allow for translational control by the COP9 signalosome.
authors.affiliation: Department of Plant Sciences, Tel Aviv University, Tel Aviv 69978, Israel.
authors.forename: A
authors.initials: A
authors.lastname: Yahalom
authors.forename: T H
authors.initials: TH
authors.lastname: Kim
authors.forename: E
authors.initials: E
authors.lastname: Winter
authors.forename: B
authors.initials: B
authors.lastname: Karniol
authors.forename: A G
authors.initials: AG
authors.lastname: von Arnim
authors.forename: D A
authors.initials: DA
authors.lastname: Chamovitz
mesh_terms: D000818:Animals; D017360:Arabidopsis / Q000378:metabolism*; D015415:Biomarkers; D000075686:COP9 Signalosome Complex; D002850:Chromatography, Gel; D039621:Eukaryotic Initiation Factor-3; D005455:Fluorescent Antibody Technique; D005656:Fungal Proteins / Q000737:chemistry; D006801:Humans; D046911:Macromolecular Substances; D008954:Models, Biological; D008969:Molecular Sequence Data; D046912:Multiprotein Complexes; D010447:Peptide Hydrolases; D010448:Peptide Initiation Factors / Q000235:genetics / Q000378:metabolism*; D010940:Plant Proteins / Q000378:metabolism*; D011233:Precipitin Tests; D039665:Prokaryotic Initiation Factor-3; D011485:Protein Binding; D021122:Protein Subunits; D021381:Protein Transport; D011506:Proteins / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D020798:Two-Hybrid System Techniques
chemical_list: D015415:Biomarkers; D039621:Eukaryotic Initiation Factor-3; D005656:Fungal Proteins; D046911:Macromolecular Substances; D046912:Multiprotein Complexes; D010448:Peptide Initiation Factors; D010940:Plant Proteins; D039665:Prokaryotic Initiation Factor-3; D021122:Protein Subunits; D011506:Proteins; D011518:Proto-Oncogene Proteins; D011993:Recombinant Fusion Proteins; D010447:Peptide Hydrolases; D000075686:COP9 Signalosome Complex