InterPro domain: IPR033858

This entry includes lid subunits of the 26 S proteasome regulatory particles, Rpn7 (PSMD7; proteasome 26S non-ATPase subunit 7; p44), and Rpn8 (PSMD8; proteasome 26S non-ATPase subunit 8; p40; Mov34). Rpn7 is known to be critical for the integrity of the 26 S proteasome complex by establishing a correct lid structure [ 1 ]. It is necessary for the incorporation/anchoring of Rpn3 and Rpn12 to the lid and essential for viability and normal mitosis. Rpn7 and Rpn8 are ATP-independent components of the 19S regulator subunit, and contain the MPN structural motif on its N-terminal region. However, while they show a typical MPN metalloprotease fold and are members of peptidase family M67, they lack the canonical JAMM motif, and therefore do not show catalytic isopeptidase activity [ 2 ]. Rpn7 is considered a non-peptidase homologue (MEROPS identifier M67.973). It is suggested that Rpn7 function is primarily structural [ 3 , 4 ].

1. Rpn7 Is required for the structural integrity of the 26 S proteasome of Saccharomyces cerevisiae. J. Biol. Chem. 279, 27168-76
2. The crystal structure of the human Mov34 MPN domain reveals a metal-free dimer. J. Mol. Biol. 370, 846-55
3. Isolation of the Schizosaccharomyces pombe proteasome subunit Rpn7 and a structure-function study of the proteasome-COP9-initiation factor domain. J. Biol. Chem. 282, 32414-23
4. Functional study of hot pepper 26S proteasome subunit RPN7 induced by Tobacco mosaic virus from nuclear proteome analysis. Biochem. Biophys. Res. Commun. 351, 405-11