Publication Abstract from PubMed
Cbl proteins are E3 ubiquitin ligases that are negative regulators of many receptor tyrosine kinases. Cbl-b and c-Cbl contain a ubiquitin-associated (UBA) domain, which is present in a variety of proteins involved in ubiquitin-mediated processes. Despite high sequence identity, Cbl UBA domains display remarkably different ubiquitin-binding properties. Here, we report the crystal structure of the UBA domain of Cbl-b in complex with ubiquitin at 1.9 A resolution. The structure reveals an atypical mechanism of ubiquitin recognition by the first helix of the UBA. Helices 2 and 3 of the UBA domain form a second binding surface, which mediates UBA dimerization in the crystal and in solution. Site-directed mutagenesis demonstrates that Cbl-b dimerization is regulated by ubiquitin binding and required for tyrosine phosphorylation of Cbl-b and ubiquitination of Cbl-b substrates. These studies demonstrate a role for ubiquitin in regulating biological activity by promoting protein dimerization.
Structural basis for ubiquitin-mediated dimerization and activation of the ubiquitin protein ligase Cbl-b.,Peschard P, Kozlov G, Lin T, Mirza IA, Berghuis AM, Lipkowitz S, Park M, Gehring K Mol Cell. 2007 Aug 3;27(3):474-85. PMID:17679095[1]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
