InterPro domain: IPR021843

This domain is typically between 142 to 163 amino acids in length is found at the C terminus of activator complex subunit 4 (gene name PSME4, PA2000 or BLM10), a component of the 19S cap complex of the eukaryotic 26S proteasome. The tertiary structure of BLM10 from Saccharomyces cerevisiae has been solved, showing that the C terminus is important for helping to form the BLM10 cap that covers the entry pore of the proteasome, restricting access for potential substrates. The C-terminal residues bind in the pocket between proteasome subunits alpha5 and alpha6, in a similar site to where the C-termini of the ATPases of the 19S proteasomal cap also bind [ 1 ].

1. Structure of a Blm10 complex reveals common mechanisms for proteasome binding and gate opening. Mol. Cell 37, 728-35