This domain is found at the C-terminal end of human Proteasome activator complex subunit 4 (PSME4) and similar sequences from eukaryotes. PSME4 is an associated component of the proteasome that specifically recognises acetylated histones and promotes ATP- and ubiquitin -independent degradation of core histones during spermatogenesis and DNA damage response. This protein adopts a dome-like structure composed of HEAT repeat-like modules and a C-terminal domain that contains a hydrophobic -tyrosine-other motif (this entry). This domain, which adopts an all-alpha structure, is responsible for the interaction with the alpha-ring surface of the 20S.
Jiyao W et al.(2023). "The conserved domain database in 2023.",