ET-3 Background Information The endothelin (ET) family of proteins are vasoactive peptides that are involved in various functions throughout the body. ET-3 (endothelin 3), also known as EDN3, is a 238 amino acid secreted protein that belongs to the endothelin family and is essential for proper neuronal development. Expressed in placental stem villi vessels and in trophoblasts, ET-3 functions as a ligand for endothelin receptor type B (ETBR) and, through this interaction, mediates the maturation of enteric neurons and melanocytes. Although ET-3 is expressed as a 238 amino acid peptide, it is post-translationally modified to produce a short active isoform and a long inactive isoform. Defects in the gene encoding ET-3 are the cause of a variety of disorders, including Hirschsprung disease type 1 (HSCR1), congenital central hypoventilation syndrome (CCHS) and Waardenburg syndrome type IV (WS4).
