lytic protease found in the cytosol and the nucleus that degrades intra-
cellular proteins conjugated to a polyubiquitin chain by an enzymatic
cascade. The 26S proteasome consists of several subunits arranged into
two 19S polar caps, where protein recognition and adenosine 5′-
triphosphate (ATP)-dependent target processing occur, flanking a 20S
central barrel-shaped structure with an inner proteolytic chamber
(Tomko and Hochstrasser 2013). The 26S proteasome participates in
the removal of misfolded or abnormally assembled proteins, the deg-
radation of cyclins involved in the control of the cell cycle, the process-
ing and degradation of transcription regulators, cellular-mediated Fig . 1 .6 A, Mitochondria in human cardiac muscle . The folded cristae
immune responses, and cell cycle arrest and apoptosis. (arrows) project into the matrix from the inner mitochondrial membrane .
B, The location of the elementary particles that couple oxidation and
Peroxisomes
phosphorylation reactions . (A, Courtesy of Dr Bart Wagner,