ET-1 Background Information
The human endothelins represent a gene family comprised of endothelin-1, endothelin-2, and endothelin-3, also known as ET-1, ET-2, and ET-3 (1). Endothelins can affect the central nervous system and neuronal excitability, and they elicit potent vasoconstrictor action (2). The two receptor subtypes responsible for inducing vasoconstriction and vasodilation, ETA and ETB, have different receptor affinities for ET-1, ET-2, and ET-3 (3). Of the three isopeptides, ET-2 has the most potent vasoconstrictor activity (1). Biologically active ETs are proteolytically generated from a larger precursor, the big-endothelin, by action of the endothelin-converting enzyme (ECE) family (5). ET-1 is a potent, 21-amino acid vasoconstrictor peptide produced by vascular endothelial cells (6). The ET-2 cDNA is 1.3 kb in length and encodes a proprotein consisting of 178 amino acid residues (1). ET3 mRNA encodes a 230-amino acid precursor that includes ET3 and a 15-amino acid homologous segment called the ET3-like sequence (7).
