Classification of Proteases
| Class (active site) | Location | Examples |
| Serine/Threonine | soluble | trypsin, chymotrypsin, subtilisin, elastase, clotting enzymes, proteasome |
| membrane | Rhomboid family | |
| Aspartic | soluble | pepsin, cathepsin, renin, HIV protease |
| membrane | presenilins, signal peptide peptidase | |
| Cysteinyl | soluble | bromelain, papain, cathespsins, caspases |
| membrane | ? | |
| Metallo | soluble | thermolysin, angiotensin converting enzyme |
| membrane | S2P family |