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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 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[]

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.

External links[]