Human angiotensin I-converting enzyme (ACE) exists in intestinal epithelial cells as a membrane-bound (ACEm) and secretory glycoprotein (ACEsec). The electrophoretic mobilities of ACEsec and ACEm on SDS/polyacrylamide gels are similar; the N-deglycosylated ACEsec and ACEm, in contrast, display slight differences in their apparent molecular masses, indicating that the carbohydrate contents of ACEsec and ACEm are different. Moreover, ACEsec is solely N-glycosylated whereas ACEm is N- and O-glycosylated, assessed by lectin binding studies. Spontaneous release of ACEsec is achieved by incubation of brush border membranes at 37 °C. Aprotinin, leupeptin and EDTA partly inhibit the generation of ACEsec, strongly suggesting that ACEsec is generated from ACEm by proteolytic cleavage. The expression levels of ACEsec in the intestine may be associated with the differentiation state of mucosal cells. Thus ACEsec is more abundant than ACEm in immature non-epithelial crypt cells of patients with coeliac disease. Well-differentiated epithelial cells, by contrast, contain predominantly ACEm. The variations in the proportions of cleaved ACEsec in differentiated and non-differentiated cells may be due to varying levels of the cleaving protease. Alternatively, because epithelial cell differentiation is accompanied by alterations in the levels of oligosaccharyltransferases, the results suggest a critical role for the glycosylation pattern of ACEm in its susceptibility to the putative cleaving protease.
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Research Article|
May 15 1996
Secretion of human intestinal angiotensin-converting enzyme and its association with the differentiation state of intestinal cells Available to Purchase
Hassan Y. NAIM
Hassan Y. NAIM
1Protein Secretion Group, Institute of Microbiology, Heinrich-Heine University of Düsseldorf, Universitätsstrasse 1, D-40225 Düsseldorf, Federal Republic of Germany
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Publisher: Portland Press Ltd
Received:
August 30 1995
Revision Received:
January 08 1996
Accepted:
January 24 1996
Online ISSN: 1470-8728
Print ISSN: 0264-6021
The Biochemical Society, London © 1996
1996
Biochem J (1996) 316 (1): 259–264.
Article history
Received:
August 30 1995
Revision Received:
January 08 1996
Accepted:
January 24 1996
Citation
Hassan Y. NAIM; Secretion of human intestinal angiotensin-converting enzyme and its association with the differentiation state of intestinal cells. Biochem J 15 May 1996; 316 (1): 259–264. doi: https://doi.org/10.1042/bj3160259
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