proteasome_protease_HslV. This group contains the eukaryotic proteosome alpha and beta subunits and the prokaryotic protease hslV subunit. Proteasomes are large multimeric self-compartmentalizing proteases, involved in the clearance of misfolded proteins, the breakdown of regulatory proteins, and the processing of proteins such as the preparation of peptides for immune presentation. Two main proteasomal types are distinguished by their different tertiary structures: the eukaryotic/archeal 20S proteasome and the prokaryotic proteasome-like heat shock protein encoded by heat shock locus V, hslV. The proteasome core particle is a highly conserved cylindrical structure made up of non-identical subunits that have their active sites on the inner walls of a large central cavity. The proteasome subunits of bacteria, archaea, and eukaryotes all share a conserved Ntn (N terminal nucleophile) hydrolase fold and a catalytic mechanism involving an N-terminal nucleophilic threonine that is exposed by post-translational processing of an inactive propeptide.
Jiyao W et al.(2023). "The conserved domain database in 2023.",