Q99075

Heparin binding epidermal-like growth factor (HBEGF), a member of the EGF family of mitogens, binds to the EGF receptor (EGFR) and to heparin sulfate proteoglycans on the cell surface. HBEGF was originally isolated from medium conditioned by the growth of the human histocytic lymphoma cell U-937 on the basis of its heparin-binding ability and its mitogenic activity for Balb-3T3 fibroblasts. The HBEGF gene encodes a 208 amino acid precursor containing a signal peptide and transmembrane domain. Mature HBEGF is a soluble protein 86 amino acids in length and results from the enzymatic cleavage of the membrane bound precursor. The membrane-bound form of HBEGF has been identified as the diphtheria toxin receptor. Preincubation of Vero cells with phorbol 12-myristate 13-acetate (PMA) induces the proteolytic cleavage of HBEGF outside the membrane anchor.