Epidermal growth factor

Epidermal growth factor or EGF is a growth factor that plays an important role in the regulation of cell growth, proliferation, and differentiation. Human EGF is a 6045-Da protein with 53 amino acid residues and three intramolecular disulfide bonds.^[1]

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Function

EGF acts by binding with high affinity to epidermal growth factor receptor (EGFR) on the cell surface and stimulating the intrinsic protein-tyrosine kinase activity of the receptor (see the second diagram). The tyrosine kinase activity, in turn, initiates a signal transduction cascade that results in a variety of biochemical changes within the cell - a rise in intracellular calcium levels, increased glycolysis and protein synthesis, and increases in the expression of certain genes including the gene for EGFR - that ultimately lead to DNA synthesis and cell proliferation.^[2]

EGF-family

EGF is the founding member of the EGF-family of proteins. Members of this protein family have highly similar structural and functional characteristics. Besides EGF itself other family members include:^[3]

• Heparin-binding EGF-like growth factor (HB-EGF)
• transforming growth factor-α (TGF-α)
• Amphiregulin (AR)
• Epiregulin (EPR)
• Epigen
• Betacellulin (BTC)
• neuregulin-1 (NRG1)
• neuregulin-2 (NRG2)
• neuregulin-3 (NRG3)
• neureguline-4 (NRG4).

All family members contain one or more repeats of the conserved amino acid sequence:

CX₇CX_4-5CX_10-13CXCX₈GXRC

Where X represents any amino acid.^[3]

This sequence contains 6 cysteine residues that form three intramolecular disulphide bonds. Disulphide bond formation generates three structural loops that are essential for high-affinity binding between members of the EGF-family and their cell-surface receptors.^[4]

EGF as Therapeutic Protein

EGF is currently being marketed as a therapeutic protein for the treatment of diabetic foot ulcers by at least three companies. Bharat Biotech International, a company based in India, is marketing EGF as REGEN-D, Daewoong Pharmaceutical, based in South Korea, is marketing EGF as Easyef, and the Center for Genetic Engineering and Biotechnology, in Cuba, is marketing EGF as CITOPROT-P.^{[5] [6]} EGF is also used in a burn treatment cream product, Hebermin, manufactured by Heber Biotec S. A. in Cuba.^[6]

References

Further reading