proteasome is a cylindrical complex containing a core of four stacked rings

circle lighting proteasome cylindrical complex core four stacked rings forming central pore rendering 3d rendering active site amino acids apoptosis background barrel black break cap cell cellular stress complex covalent cylindrical degradation degrade destruction chamber enzyme enzymes health healthy isolated ligase medical molecular molecular structure molecule organic peptide peptides protease proteasome protein proteolysis regulation regulatory particles response science tube ubiquitin ubiquitin system