Creating a Soluble Binder to Endothelin-1 Based on the Natural Ligand Binding Domains of the Endothelin-1 (G-Protein-Coupled) Receptor.

Since its discovery in 1989, there has been extensive research on endothelin (ET)-1 physiology, as well as pathology. Accordingly, there is considerable research on the discovery of therapeutics based around ET-1, amongst which current treatment options include endothelin receptor antagonists. These target the ET-1 receptors, which are G-protein–coupled receptors (GPCRs). We have effectively developed a soluble form of a GPCR that binds to ligands, by constructing a fusion polypeptide of different endothelin receptor ligand binding domains. Phage experiments identified strong binders to ET-1. We then constructed Fc-fusions of the top binders and further binding assays revealed a KD of 21.2 nM for the Fc-ETtr1 construct and KD of 77.3 nM for the Fc-ETtr2 construct. These constructs are soluble and have the ability to bind and potentially sequester elevated ET-1 levels that are prevalent in different diseases. These results provide a novel approach to targeting GPCR–binding ligands, and thereby to contribute to a very important class of therapeutics.