26S proteasome plays a major role in eukaryotic protein breakdown, especially for ubiquitin-tagged proteins. It is an ATP-dependent protease responsible for the bulk of non-lysosomal proteolysis in eukaryotes, often using covalent modification of proteins by ubiquitylation. It consists of a 20S proteolytic core particle (CP) and a 19S regulatory particle (RP). The CP is an ATP independent peptidase consisting of hydrolyzing activities. One or both ends of CP carry the RP that confers both ubiquitin and ATP dependence to the 26S proteosome. The RP's proposed functions include recognition of substrates and translocation of these to CP for proteolysis. The RP can dissociate into a stable lid and base subcomplexes. The base is composed of three non-ATPase subunits (Rpn 1, 2 and 10). A single residue in the vWA domain of Rpn10 has been implicated to be responsible for stabilizing the lid-base association.
Jiyao W et al.(2023). "The conserved domain database in 2023.",