New Insights into the Function of the Immunoproteasome in Immune and Nonimmune Cells

Figure 1

Structure of the constitutive proteasome and the immunoproteasome. The constitutive proteasome is composed of two pairs of inner β-rings, two pairs of outer α-rings, and two caps (19S regulatory complexes). Inflammatory cytokines induce the expression of the five subunits (iβ1 [LMP2], iβ2 [LMP10], iβ5 [LMP7], PA28α, and PA28β), which assemble on the proteasome core to create the immunoproteasome. When the induced subunits replace the β subunits and 19S regulatory complex, the resulting multiprotein complex is called the immunoproteasome.