title: Targeting of protein ubiquitination by BTB-Cullin 3-Roc1 ubiquitin ligases.
abstract: The concentrations and functions of many cellular proteins are regulated by the ubiquitin pathway. Cullin family proteins bind with the RING-finger protein Roc1 to recruit the ubiquitin-conjugating enzyme (E2) to the ubiquitin ligase complex (E3). Cul1 and Cul7, but not other cullins, bind to an adaptor protein, Skp1. Cul1 associates with one of many F-box proteins through Skp1 to assemble various SCF-Roc1 E3 ligases that each selectively ubiquitinate one or more specific substrates. Here, we show that Cul3, but not other cullins, binds directly to multiple BTB domains through a conserved amino-terminal domain. In vitro, Cul3 promoted ubiquitination of Caenorhabditis elegans MEI-1, a katanin-like protein whose degradation requires the function of both Cul3 and BTB protein MEL-26. We suggest that in vivo there exists a potentially large number of BCR3 (BTB-Cul3-Roc1) E3 ubiquitin ligases.
authors.affiliation: Lineberger Comprehensive Cancer Center, Department of Biochemistry and Biophysics, and Program in Molecular Biology and Biotechnology, University of North Carolina at Chapel Hill, NC 27599-7295, USA.
authors.forename: Manabu
authors.initials: M
authors.lastname: Furukawa
authors.forename: Yizhou Joseph
authors.initials: YJ
authors.lastname: He
authors.forename: Christoph
authors.initials: C
authors.lastname: Borchers
authors.forename: Yue
authors.initials: Y
authors.lastname: Xiong
mesh_terms: D000818:Animals; D017173:Caenorhabditis elegans; D029742:Caenorhabditis elegans Proteins / Q000378:metabolism*; D002478:Cells, Cultured; D025801:Ubiquitin / Q000378:metabolism*; D044767:Ubiquitin-Protein Ligases / Q000378:metabolism*
chemical_list: D029742:Caenorhabditis elegans Proteins; D025801:Ubiquitin; D044767:Ubiquitin-Protein Ligases