In eukaryotic cells, selective breakdown of cellular proteins is ensured by their ubiquitination and subsequent degradation by the 26S Proteasome. The 26S Proteasome is a protease complex that selectively breaks down proteins that have been modified by polyubiquitin chains. It is made up of two multisubunit complexes: the 20S Proteasome chamber, which serves as the proteolytic core of the complex and two 19S regulatory particles which recognize and unfold ubiquitinated proteins. The 20S Proteasome chamber contains α subunits (which are structural) and β subunits (which are predominantly catalytic). The outer two rings in the proteasome consist of seven α subunits each, and the inner two rings each consist of seven β subunits. PSMB6 (proteasome (prosome, macropain) subunit, β type, 6), also known as LMPY (PSY large multifunctional protease Y), macropain δ chain, proteasome δ chain or proteasome subunit Y, is a β subunit of the 20S Proteasome and, upon stimulation with IFN-γ, can be displaced by LMP2.