The COP9 signalosome (CSN) is composed of eight distinct subunits and is highly homologous to the lid sub-complex of the 26S proteasome. CSN was initially defined as a repressor of photomorphogenesis in Arabidopsis, and it has now been found to participate in diverse cellular and developmental processes in various eukaryotic organisms. Recently, CSN was revealed to have a metalloprotease activity centered in the CSN5/Jab1 subunit, which removes the post-translational modification of a ubiquitin-like protein, Nedd8/Rub1, from the cullin component of SCF ubiquitin E3 ligase (i.e., de-neddylation). In addition, CSN is associated with de-ubiquitination activity and protein kinase activities capable of phosphorylating important signaling regulators. The involvement of CSN in a number of cellular and developmental processes has been attributed to its control over ubiquitin-proteasome-mediated protein degradation.

中文翻译：

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COP9信号小体。

COP9信号小体（CSN）由八个不同的亚基组成，与26S蛋白酶体的盒盖亚复合物高度同源。CSN最初被定义为拟南芥中光形态发生的阻遏物，现在发现它参与了各种真核生物中的各种细胞和发育过程。最近，发现CSN具有以CSN5 / Jab1亚基为中心的金属蛋白酶活性，该活性从SCF泛素E3连接酶的cullin成分中去除了泛素样蛋白Nedd8 / Rub1的翻译后修饰。 neddylation）。此外，CSN与去泛素化活性和能够使重要的信号调节因子磷酸化的蛋白激酶活性有关。