Proteases and Protease Inhibitors

This chapter discusses the potential functions of proteases and protease inhibitors within the seminiferous epithelium. Proteolysis is one of several important posttranslational modifications that a protein can undergo during its lifetime. Proteolysis is the consequence of the opposing actions of proteases and their complementary inhibitors. Ubiquitously expressed in all biological tissues and fluids, proteases are enzymes capable of catalytically cleaving peptide bonds in proteins. Because of their enzymatic activities, proteases play major roles in the differentiation and function of all cells and tissues, and they can have a profound effect on the interactions of cells with their immediate microenvironments. These enzymes are essential for the remodeling or degradation of basement membranes, and consequently, the movement of cells within an epithelium. Specific proteases can also modify cell–substrate and cell–cell interactions by degrading or activating cell adhesion molecules, procytokines, and cell surface receptors. A protease often acts in cooperation with a network of other proteins, including their complementary inhibitors.