Proteolysis is the directed degradation (digestion) of proteins by cellular enzymes called proteases or by intramolecular digestion.

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 proteases are trypsin and chymotrypsin.

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 effectsHayes WK. 2005. Research on Biological Roles and Variation of Snake Venoms. Loma Linda University., including:

• cytotoxic (cell-destroying)
• hemotoxic (blood-destroying)
• myotoxic (muscle-destroying)
• hemorrhagic (bleeding)

See also

• Proteasome

Notes