This entry represents proteasome activator complex subunit 4 (gene name PSME4, PA2000 or BLM10), which is particularly associated with thespermatoproteasome. PSME4 binds acetylated histones which are degraded by the proteasome during spermatogenesis. Histones are bound via the bromodomain-like region. PSME4 also activates the proteasome, permitting entry of substrate into the internal chamber where degradation occurs []. PSME4 is also required for the degradation of histones during the DNA damage response in somatic cells []. The structure of the yeast BLM10/proteasome complex has been solved, and shows that BLM10 forms a dome structure over the proteasome entry pore, restricting access for potential substrates and inducing a disordered gate structure [].
