InterPro domain: IPR035309

This entry represents proteasome activator complex subunit 4 (gene name PSME4, PA2000 or BLM10), which is particularly associated with the spermatoproteasome. 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 [ 1 ]. PSME4 is also required for the degradation of histones during the DNA damage response in somatic cells [ 2 ]. 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 [ 2 ].

1. Acetylation-mediated proteasomal degradation of core histones during DNA repair and spermatogenesis. Cell 153, 1012-24
2. Structure of a Blm10 complex reveals common mechanisms for proteasome binding and gate opening. Mol. Cell 37, 728-35