Proteolysis
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Proteolysis is the directed degradation (digestion) of proteins by cellular enzymes called proteases or by intramolecular digestion.
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[edit] Purposes
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.
[edit] Examples
Examples of proteases include:
[edit] Venoms
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[1], including:
- cytotoxic (cell-destroying)
- hemotoxic (blood-destroying)
- myotoxic (muscle-destroying)
- hemorrhagic (bleeding)
[edit] See also
[edit] References
- ^ Hayes WK. 2005. Research on Biological Roles and Variation of Snake Venoms. Loma Linda University.
