Mouse Epigen Antibody (187240)

Epigen (EPGN) is an epithelial mitogen that belongs to the EGF superfamily (1-3). Mouse Epigen cDNA encodes a 152 amino acid (aa) residue type I transmembrane precursor protein with a 23 aa putative signal peptide, an 86 aa extracellular domain, a 21 aa transmembrane domain and a 22 aa cytoplasmic domain (2, 3). The extracellular domain (aa 24-109) contains a pattern of six cysteines typical of EGF family proteins (1-3). Epigen is among several EGF family proteins that can undergo metalloproteinase cleavage to generate a soluble form (3, 4). Cleavage of Epigen by TACE/ADAM17 has been demonstrated (4). The mature, shed form of mouse Epigen (aa 53-103) shares 92%, 96% and 90% aa sequence identity with human, rat and equine Epigen, respectively, and more than 40% aa identity with corresponding regions of TGF-alpha and epiregulin (2). Epigen mRNA is found in many tissues, but it is mainly expressed in actively proliferating cells within these tissues. For example, Epigen in skin is found mainly in the proliferating root sheath of hair follicles, and transgenic overexpression in the skin causes hyperplasia in sebaceous glands (3, 5). Epigen is also expressed developmentally and by invasive adenocarcinomas of the breast and prostate (3). Epigen is strongly mitogenic for epithelial cells and fibroblasts, despite its relatively weak affinity for its main receptor, ErbB1 (2, 3). The mitogenic potential of Epigen is enhanced by its unusually long persistence on the membrane before ubiquitylation and receptor-mediated depletion (3).