PSMB8 (Proteasome Subunit beta type-8; Also beta 5i, RING10/Y2 and LMP7) is a 23-24kD member of the peptidase T1B family of molecules. It is expressed both constitutively and inducibly by IFN-gamma in a wide variety of cells, including immature dendritic cells, preadipocytes, CD4+ T cells and monocytes. LMP7 is a subunit of the 700kD, 20S proteasome catalytic complex, a dynamic intracellular structure that participates in ATP-dependent proteolytic activity. LMP7 qualifies as a beta­type, i (immuno)-type proteasome, meaning it both plays a chymotrypsin-like role in the turnover of proteins and is found in cytokine­responsive cells. The peptides generated through LMP7 activity are presented as antigens by MHC-I molecules. LMP7 activity is dependent upon the removal of the LMP7 precursor prosequence, an action that exposes a critical internal Thr residue. Human LMP7 is synthesized as a 28-29kD, 276 amino acid (aa) proprecursor. It contains a 72aa autocleavable propeptide plus a 204aa mature region. There is one alternative splice form that shows a 45 aa substitution for aa1-49. This isoform does not appear to participate in formation of a proteosome. Over aa73-276, human LMP7 shares 92% aa sequence identity with mouse LMP7.