Localization and biochemical characterization of endothelin-converting enzyme

Abstract

We used a variety of biochemical and immunologic techniques to investigate the localization of endothelin-converting enzyme (ECE) in porcine lung, in human umbilical vein endothelial cells (HUVECs), and in the transformed endothelial cell line EA.hy926. Phosphoramidon-sensitive ECE activity was not enriched on immunomagnetically separated angiotensin-converting enzyme (ACE)-bearing luminal endothelial membranes from pig lung, whereas ACE showed a sevenfold enrichment. ECE activity did, however, co-localize with aminopeptidase-N (AP-N) activity on isolated EA.hy926 plasma membranes. Using a monoclonal antibody to rat lung ECE (AEC32-326) and immunofluorescence microscopy, we have demonstrated ECE on the cell surface of endothelial cell lines.