The Proper functioning of a cell requires careful control of the levels of important structural proteins, enzymes, and regulatory proteins. Protein molecules are continuously synthesised and degraded in all living organisms. The concentration of individual cellular proteins is determined by a balance between the rates of synthesis and degradation, which in turn are controlled by a series of regulated biochemical mechanisms. Differences in the rates of protein synthesis and breakdown result in cellular and tissue atrophy (loss of proteins from cells) and hypertrophy (increase in protein content of cells). Precise control of protein turnover is, therefore, essential to cellular survival. The only way that cells can reduce the excessive level of a particular protein is by proteolytic degradation. Although protein [...]