Phosphoramidon-sensitive endothelin-converting enzyme in vascular endothelial cells converts big endothelin-1 and big endothelin-3 to their mature form.
Incubation of big endothelin-3 (big ET-3(1-41)) with the membrane fraction obtained from cultured endothelial cells (ECs) resulted in an increase in immunoreactive-ET (IR-ET). This increasing activity was markedly suppressed by phosphoramidon, which is known to inhibit the conversion of big ET-1(1-39) to ET-1(1-21). Reverse-phase HPLC of the incubation mixture of the membrane fraction with big ET-3 revealed one major IR-ET component corresponding to the elution position of synthetic ET-3(1-21). When the cultured ECs were incubated with big ET-3, a conversion to the mature ET-3, as well as an endogenous ET-1 generation, was observed. Both responses were markedly suppressed by phosphoramidon. By the gel filtration of 0.5% CHAPS-solubilized fraction of membrane pellets of ECs, the molecular mass of the proteinase which converts big ET-1 and big ET-3 to their mature form was estimated to be 300-350 kDa. Phosphoramidon almost completely abolished both converting activities of the proteinase. We conclude that the above type of phosphoramidon-sensitive metalloproteinase functions as an ET-converting enzyme to generate the mature form from big ET-1 and big ET-3 in ECs.
Matsumura
Y
Y
Department of Pharmacology, Osaka University of Pharmaceutical Sciences, Japan.
Tsukahara
Y
Y
Kuninobu
K
K
Takaoka
M
M
Morimoto
S
S
D000818:Animals; D001011:Aorta / Q000201:enzymology; D002851:Chromatography, High Pressure Liquid; D019332:Endothelin-1; D016232:Endothelins / Q000378:metabolism*; D004730:Endothelium, Vascular / Q000201:enzymology*; D006020:Glycopeptides / Q000494:pharmacology; D015260:Neprilysin / Q000037:antagonists & inhibitors / Q000187:drug effects / Q000378:metabolism*; D011498:Protein Precursors / Q000378:metabolism*; D011863:Radioimmunoassay; D013552:Swine
D019332:Endothelin-1; D016232:Endothelins; D006020:Glycopeptides; D011498:Protein Precursors; D015260:Neprilysin; C008890:phosphoramidon