Apcher Géraud-Sébastien, Maitland Joanne, Dawson Simon, Sheppard Paul, Mayer R John
Laboratory of Intracellular Proteolysis, School of Biomedical Sciences, University of Nottingham, Medical School, Queen's Medical Centre, Nottingham NG7 2UH, UK.
FEBS Lett. 2004 Jul 2;569(1-3):211-6. doi: 10.1016/j.febslet.2004.05.067.
The detailed mechanism of eukaryotic 20S proteasome assembly is currently unknown. In the present study, we demonstrate that the 20S proteasome subunits alpha4 and alpha7 interact with each other as well as all the alpha-subunits in vivo and in vitro. The N-terminal parts of alpha4 and alpha7 are essential for these newly discovered interactions in vitro. Glycerol gradient centrifugation of soluble extracts of HEK293 cells and Western blot analyses show that several alpha-subunits are found in non-proteasomal low-density fractions. The alpha4 and alpha7 subunits co-immunoprecipitate together from these low-density fractions. The unexpected interaction between alpha4 and alpha7 may provide a molecular basis for the formation of previously reported 13S and 16S assembly intermediates.
真核生物20S蛋白酶体组装的详细机制目前尚不清楚。在本研究中，我们证明20S蛋白酶体亚基α4和α7在体内和体外相互作用，并且与所有α亚基相互作用。α4和α7的N端部分对于体外这些新发现的相互作用至关重要。对HEK293细胞可溶性提取物进行甘油梯度离心和蛋白质印迹分析表明，在非蛋白酶体低密度组分中发现了几个α亚基。α4和α7亚基从这些低密度组分中共免疫沉淀。α4和α7之间意外的相互作用可能为先前报道的13S和16S组装中间体的形成提供分子基础。
