| Popis: |
Epidermal growth factor (EGF) was the first member identified of a family of growth factors which exert their effects via a single 170,000 Mr plasma membrane receptor (for review see Todaro et al. 1990). Other members include transforming growth factor alpha (TGF-α), amphiregulin (AR) and several viral growth factors. TGF-α is a peptide with a MW of about 5600 which shares 30% structural homology with EGF and has the three disulfide bonds that are characteristic for this family. However, EGF and TGF-α differ somewhat in their mechanism of binding to the EGF receptor and also have slightly different effects on their target cells (for review see Derynck 1988, Winkler et al. 1989). Another, new member of the EGF family is amphiregulin (AR). AR is a glycosylated, 84-amino acid polypeptide growth regulator which has sequence homology to the EGF family of proteins (Johnson et al. 1992). AR inhibits growth of some tumor cells but also stimulates growth of the normal keratocytes and fibroblasts. |
