Proteolysis is used by the cell for several purposes. They include:
- Removal of N-terminal methionine residues after translation.
- Removal of the signal sequence of peptides after their transport through a membrane
- Separation of viral proteins that were translated from a monocistronic mRNA
- Digestion of proteins from foods as a source of amino acids
- Conversion of predecessor-proteins (proenzymes, zymogens, prehormones) into their final structures.
- Degradation of cyclins at different stages of the cell cycle.
Examples of serine proteases include:
Certain venoms, such as those produced by poisonous snakes, can also cause proteolysis. These venoms are, in fact, highly-evolved digestive fluids that begin their work outside of the body. Proteolytic venoms cause a wide range of toxic effects, including effects that are:
- cytotoxic (cell-destroying)
- hemotoxic (blood-destroying)
- myotoxic (muscle-destroying)
- hemorrhagic (bleeding)
- ↑ Hayes WK. 2005. Research on Biological Roles and Variation of Snake Venoms. Loma Linda University.