Is an ortholog of human PSMD4 (proteasome 26S subunit, non-ATPase 4). Is predicted to have polyubiquitin modification-dependent protein binding activity. Is involved in spermatogenesis and ubiquitin-dependent protein catabolic process. Localizes to the cytoplasm and nucleus. Is expressed in the alimentary system\; the body wall musculature\; the excretory cell\; the hypodermis\; and the reproductive system.