What are Proteases?
Proteases are enzymes that catalyze the hydrolysis of peptide and isopeptide bonds that link amino acids within proteins, in the process referred to as proteolysis. Proteases have evolved as multifunctional enzymes adapting and diversifying to various biological roles resultant of changes in their expression patterns, substrate specificities and structure-function relationships.
Role of Proteases
- Activating cytokines and receptors for cell signaling.
- Cell death mediators and Antigen processors :
Activation of Bid in apoptosis by Caspases-8, Calpains & Cathepsins B, L S, H, D, acting via the loops or interdomain linker regions.
Processing antigens via the lysosomal system for presentation by MHC class II molecules, such as cathepsins and deubiquitinating enzymes.
- Ectodomain processors by exposing cryptic sites, such as beta-secretase during amyloid precursor protein processing or Shedding various transmembrane proteins such as metalloproteases and cysteine proteases.
- ECM modulators by using exosites as effective substrate binding, such as thrombin, ADAMTS-4 and most MMPs.
- Targets for viral inhibitors to arrest viral proteases processing viral polyproteins in causing pathogenicity
Figure. Schematic representation of diverse roles of Proteases.