10 - Insect Proteases

Abstract

This chapter focuses on non-digestive proteases, which have many diverse roles in insect biology. Proteases (peptidases) are enzymes that hydrolyze peptide bonds in proteins. These proteases often function in cascade pathways, in which one protease activates the zymogen form of another protease, leading to amplification of an initial signal that may involve a few molecules, and finally generating a very large number of effector molecules at the end of the pathway. The complement and blood coagulation pathways in mammals are well-understood examples of this type of protease cascade, which also occurs in insect embryonic development and insect immune responses. Details of the organization and regulation of such pathways in insect biology are beginning to be understood in a few species. A common feature of proteases is that they are synthesized as inactive zymogens, activated by proteolysis when the time is right, and then rapidly inhibited by specific inhibitors. Better understanding of molecular mechanisms of this tight regulation of multiple and varied protease cascade pathways will impact many areas of insect biology.