Receptor for endothelin-1. Mediates its action by association with G proteins that activate a phosphatidylinositol-calcium second messenger system. The rank order of binding affinities for ET-A is: ET1 > ET2 >> ET3.
Subcellular locations: Cell membrane
Isoform 1, isoform 3 and isoform 4 are expressed in a variety of tissues, with highest levels in the aorta and cerebellum, followed by lung, atrium and cerebral cortex, lower levels in the placenta, kidney, adrenal gland, duodenum, colon, ventricle and liver but no expression in umbilical vein endothelial cells. Within the placenta, isoform 1, isoform 2, isoform 3 and isoform 4 are expressed in the villi and stem villi vessels.