Anti-peptide antibodies specific to rat endothelin-converting enzyme-1 isoforms reveal isoform localisation and expression.

Endothelin-converting enzyme-1 (ECE-1) is a critical enzyme in the biosynthesis of the potent vasoconstrictor peptide endothelin and exists in several isoforms. Anti-peptide antibodies raised against epitopes in the distinct N-terminal cytoplasmic tails of the rat ECE-1 isoforms have been obtained. By using these antibodies in Western blot analysis and immunofluorescence studies, we have shown that cultures of transformed rat lung vascular endothelial cells treated with the metalloprotease inhibitor phosphoramidon and untreated cells express ECE-1alpha only, whereas human umbilical vein endothelial cells express ECE-1alpha and ECE-1beta. The ECE-1 isoforms expressed in CHO-K1 cells transfected with rat cDNA to ECE-1alpha and ECE-1beta could be immunoprecipitated by using the appropriate isospecific antibody.