Department of Pathology, New York University Cancer Institute and New York University School of Medicine, New York 10016, USA.
Cell Div. 2006 Apr 28;1:5. doi: 10.1186/1747-1028-1-5.
Ubiquitylation targets proteins for degradation by the 26S proteasome. Some yeast and plant ubiquitin ligases, including the highly conserved SCF (Skp1/Cul1/F-box protein) complex, have been shown to associate with proteasomes. We sought to characterize interactions between SCF complexes and proteasomes in mammalian cells.
We found that the binding of SCF complexes to proteasomes is conserved in higher eukaryotes. The Cul1 subunit associated with both sub-complexes of the proteasome, and high molecular weight forms of Cul1 bound to the 19S proteasome. Cul1 is ubiquitylated in vivo. Ubiquitylation of Cul1 promotes its binding to the S5a subunit of the 19S sub-complex without affecting Cul1 stability.
The association of ubiquitylating enzymes with proteasomes may be an additional means to target ubiquitylated substrates for degradation.
泛素化将蛋白质靶向 26S 蛋白酶体进行降解。一些酵母和植物泛素连接酶，包括高度保守的 SCF（Skp1/Cul1/F-box 蛋白）复合物，已被证明与蛋白酶体相关。我们试图描述哺乳动物细胞中 SCF 复合物与蛋白酶体之间的相互作用。
我们发现，SCF 复合物与蛋白酶体的结合在高等真核生物中是保守的。Cul1 亚基与蛋白酶体的两个亚基复合物都有关联，并且 Cul1 的高分子量形式与 19S 蛋白酶体结合。Cul1 在体内被泛素化。Cul1 的泛素化促进其与 19S 亚基复合物的 S5a 亚基结合，而不影响 Cul1 的稳定性。
将泛素化酶与蛋白酶体结合可能是另一种将泛素化底物靶向降解的方法。
