ECE1, Endothelin-converting enzyme 1, also known as ECE. It is located in cell membrane, and it has 4 isoforms. All isoforms are expressed in umbilical vein endothelial cells, polynuclear neutrophils, fibroblasts, atrium cardiomyocytes and ventricles. Isoforms A, B and C are also expressed in placenta, lung, heart, adrenal gland and phaeochromocytoma; isoforms A and C in liver, testis and small intestine; isoform B, C and D in endothelial cells and umbilical vein smooth muscle cells; isoforms C and D in saphenous vein cells, and isoform C in kidney (PMID: 9396733). The protein encoded by this gene is involved in proteolytic processing of endothelin precursors to biologically active peptides. Mutations in this gene are associated with Hirschsprung disease, cardiac defects and autonomic dysfunction. Alternatively spliced transcript variants encoding different isoforms have been noted for this gene. The calculated molecular weight of ECE1 is 87 kDa, as a result of glycosylation, the apparent molecular mass of ECE1 is approximately 87-110 kDa.