Figure 2.

Proteasome inhibition. (A) Schematic representation of the binding channel of the constitutive proteasome (left) and the immunoproteasome (right) containing a representative peptide sequence. The catalytically active Thr1 and the scissile peptide bond are highlighted in red. The selectivity pockets are depicted in blue. Met45 adopts a different conformation in the immunoproteasome widening the S1 pocket. The unique Cys48 in the immunoproteasome S4 pocket is shown explicitly. (B) Chemical structures of known proteasome inhibitors (cCP). P sites have been matched with the corresponding S pockets.