Fig. 2.

Structure of the 20S proteasome. This image shows the mammalian (bovine) 20S proteasome as a reconstruction from X-ray crystallographic data with a resolution of 2.75 Å [197]. The left panel shows the structure of this large multicatalytic protease complex with color-coded individual subunits from a side-view including its dimensions. The center panel shows a cross section with several removed alpha and beta subunits and the right panel shows a greyscale image of that cross-section for a better visualization of the inner structure, subdivided into two fore chambers, separated by the gate from the environment and the central main chamber where the proteolytic centers are localized facing the inside of the proteasome.