InterPro domain: IPR040134

The 26S proteasome consists of a 20S proteolytic core particle (CP) and a 19S regulatory particle (RP). The RP can be further divided into two subcomplexes, the base that directly associates with the CP and a peripheral lid. The RP lid is structurally similar to the COP9 signalosome (CSN). The core CSN subunits (CSN4/5/7/6) show a remarkable one-to-one sequence correspondence with those of the RP lid (RPN5/11/9/8), suggesting a common ancestry and architecture [ 1 ].

This family includes the 26S Proteasome non-ATPase regulatory subunit 12 (PSMD12 or RPN5), a component of the 26S proteasome lid [ 2 ], and the COP9 signalosome subunit 4 [ 3 ].

1. Subunit interaction maps for the regulatory particle of the 26S proteasome and the COP9 signalosome. EMBO J. 20, 7096-107
2. Structure of the human 26S proteasome at a resolution of 3.9 A. Proc. Natl. Acad. Sci. U.S.A. 113, 7816-21
3. The COP9 signalosome: more than a protease. Trends Biochem. Sci. 33, 592-600