Proteolysis

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

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 polycistronic 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

Examples of serine proteases include:

• trypsin
• chymotrypsin
• elastase

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 effects that are:

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

See also

• Proteasome

References

1. ^ Hayes WK. 2005. Research on Biological Roles and Variation of Snake Venoms. Loma Linda University.