Functional significance of the isoforms of endothelin-converting enzyme-1

The subcellular localization of endothelin-converting enzyme-1 (ECE-1) is a matter of some controversy, further complicated by the discovery of its multiple isoforms. ECE-1 is a critical enzyme in the biosynthesis of the potent vasoconstrictor peptide endothelin (ET), and, as such, represents a potential target for drug therapy in the control of disease states involving the ET system. Knowledge of the precise locations of the isoforms and their regulation would aid in the design of drugs to target specifically ECE-1. In this study, the subcellular localization and potential targeting pathways of the ECE-1 isoforms were investigated. Antipeptide antibodies were raised to the unique N-terminal sequence of ECE-1b and were then used in the investigation of its subcellular distribution. Mutagenesis of proposed targeting sequences within the cytoplasmic tails of the isoforms was carried out to determine their significance in subcellular localization.