Ubiquitin D （UBD） is an ubiquitin-like modifier （UBL） of the ubiquitin protein family. UBD is an ubiquitin-like protein which can form covalent conjugates， thus targeting proteins for degradation by the 26S proteasome. It is assumed that， UBD has roles in regulation of cell cycle， innate immunity， and apoptosis. UBD is a TNF-a inducible ubiquitin-like protein with a presumed role in the immune response.
