Chapter 6 Intracellular proteolysis

Publisher Summary Intracellular proteolysis is extensive and selective. It depends on the activity and the amount of proteinases and their inhibitors and on the conformation of the substrate proteins. It may be regulated by many effectors including substrates, cosubstrates, and products of these substrate proteins. Energy dependence and compartmentation are also important for the regulation of intracellular proteolysis. The expenditure of energy involved in this extensive turnover of cell proteins must be balanced by several metabolic advantages, such as the capacity to regulate metabolic pathways. In nongrowing organisms, intracellular proteolysis is necessary to adapt the protein composition to environmental changes. Consequently, one group of proteins can be replaced by another more appropriate group without extensive changes in the total amount of intracellular proteins. In addition, intracellular proteolysis allows a correction of errors in transcription or translation or in posttranslational events and it allows the liberation of amino acids as an energy source from superfluous protein molecules.