An EGF-like growth factor (208 aa) that stimulates smooth muscle cell proliferation. The factor is synthesized as a type I transmembrane protein (proHB-EGF) and expressed on the cell surface; the ectodomain is shed following cleavage by a metallopeptidase and will bind to and activate the EGF receptors HER-1 and HER-4. Soluble HB-EGF will bind heparin and other connective tissue macromolecules such as heparan sulphate and this immobilization may produce a local concentration greater than that of soluble factors. The cytoplasmic domain of proHB-EGF (HB-EGF-cyto) interacts with transcriptional repressors to reverse their repressive activities. The precursor is the binding site for diptheria toxin.
Subjects: Medicine and Health.