Kang Yang, Chen Xiang, Lary Jeffrey W, Cole James L, Walters Kylie J
Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA.
J Mol Biol. 2007 May 25;369(1):168-76. doi: 10.1016/j.jmb.2007.03.008. Epub 2007 Mar 12.
Ubiquitin receptors connect substrate ubiquitylation to proteasomal degradation. HHR23a binds proteasome subunit 5a (S5a) through a surface that also binds ubiquitin. We report that UIM2 of S5a binds preferentially to hHR23a over polyubiquitin, and we provide a model for the ternary complex that we expect represents one of the mechanisms used by the proteasome to capture ubiquitylated substrates. Furthermore, we demonstrate that hHR23a is surprisingly adept at sequestering the ubiquitin moieties of a polyubiquitin chain, and provide evidence that it and the ubiquitylated substrate are committed to each other after binding.
泛素受体将底物泛素化与蛋白酶体降解联系起来。HHR23a通过一个也能结合泛素的表面与蛋白酶体亚基5a（S5a）结合。我们报告称，S5a的UIM2优先于多聚泛素与hHR23a结合，并且我们提供了一个三元复合物模型，我们认为该模型代表了蛋白酶体捕获泛素化底物所使用的机制之一。此外，我们证明hHR23a惊人地擅长隔离多聚泛素链的泛素部分，并提供证据表明它与泛素化底物在结合后相互作用。
