COP9 signalosome complex subunit 8 isoform 1, also known as COPS8, is one of the eight subunits of COP9 signalosome, a highly conserved protein complex that functions as an important regulator in multiple signaling pathways. The structure and function of COP9 signalosome is similar to that of the 19S regulatory particle of 26S proteasome. COP9 signalosome has been shown to interact with SCF-type E3 ubiquitin ligases and act as a positive regulator of E3 ubiquitin ligases. Recombinant human COPS8 protein, fused to His-tag at N-terminus, was expressed in E.coli.