Eukaryotic proteasomes have three different types of active sites: two chymotrypsin‐like, two
trypsin‐like, and two caspase‐like (also termed PGPH) sites that differ in their specificity
toward model fluorogenic peptide substrates. The chymotrypsin‐like site is often considered
the most important in protein breakdown, and the only one whose activity has to be assayed
in order to assess the capacity of proteasomes to degrade proteins. However, recent results
indicate that either trypsin‐like or caspase‐like sites also have to be inhibited in order to …