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First published online December 23, 2004; 10.1104/pp.104.052654 Plant Physiology 137:83-93 (2005) © 2005 American Society of Plant Biologists Arabidopsis AtCUL3a and AtCUL3b Form Complexes with Members of the BTB/POZ-MATH Protein Family1Angewandte Genetik, Freie Universität Berlin, 14195 Berlin, Germany
The ubiquitin proteasome pathway in plants has been shown to be important for many developmental processes. The E3 ubiquitin-protein ligases facilitate transfer of the ubiquitin moiety to substrate proteins. Many E3 ligases contain cullin proteins as core subunits. Here, we show that Arabidopsis (Arabidopsis thaliana) AtCUL3 proteins interact in yeast two-hybrid and in vitro pull-down assays with proteins containing a BTB/POZ (broad complex, tramtrack, bric-a-brac/pox virus and zinc finger) motif. By changing specific amino acid residues within the proteins, critical parts of the cullin and BTB/POZ proteins are defined that are required for these kinds of interactions. In addition, we show that AtCUL3 proteins assemble with the RING-finger protein AtRBX1 and are targets for the RUB-conjugation pathway. The analysis of AtCUL3a and AtCUL3b expression as well as several BTB/POZ-MATH genes indicates that these genes are expressed in all parts of the plant. The results presented here provide strong evidence that AtCUL3a and AtCUL3b can assemble in Arabidopsis with BTB/POZ-MATH and AtRBX1 proteins to form functional E3 ligases.
1 This work was supported by the Deutsche Forschungsgemeinschaft (grant nos. HE3224/12 to P.H. and HE3224/11 to H.H.) and by the National Science Foundation (grant no. DBI0115870 to M.E.). 2 Present address: Angewandte Genetik, Freie Universität Berlin, 14195 Berlin, Germany. 3 Present address: Institut de Biologie Moléculaire des Plantes du CNRS, 67084 Strasbourg, France. 4 Present address: Department of Biology, Indiana University, Bloomington, IN 47405. Article, publication date, and citation information can be found at www.plantphysiol.org/cgi/doi/10.1104/pp.104.052654. * Corresponding author; e-mail hellmann{at}zedat.fu-berlin.de; fax 493083854345. Received August 31, 2004; returned for revision November 15, 2004; accepted November 22, 2004. This article has been cited by other articles:
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