This volume brings together a set of reviews that provide a summary of our current knowledge of the proteolytic machinery and of the pathways of protein breakdown of prokaryotic and eukaryotic cells. Intracellular protein degradation is much more than just a mechanism for the removal of incorrectly folded or damaged proteins. Since many short-lived proteins have important regulatory functions, proteolysis makes a significant contribution to many cellular processes including cell cycle regulation and transciptional control. In addition, limited proteolytic cleavage can provide a rapid and...