One of the endothelin gene family, endothelin 3 gene, is expressed in the placenta.

A cDNA encoding human endothelin 3 (ET-3) precursor was cloned from a cDNA library from the placenta, and its nucleotide and deduced amino acid sequences were determined. This ET-3 cDNA was found to contain 2.3 kb pairs and encode prepro-ET-3 protein consisting of 224 amino acid residues. The putative big-ET-3 seems to consist of 42 amino acid residues. Two of the intron insertion sites were determined with information from nucleotide sequences of the cloned genomic ET-3 gene. This is the first direct evidence that the ET-3 gene is transcribed and expressed in the placenta.