The Presence of Insulin-degrading Enzyme in Human Ileal and Colonic Mucosal Cells

Jane P F Bai, Hae Jin Hong, David A. Rothenberger, W. Douglas Wong, John G. Buls

Research output: Contribution to journalArticlepeer-review

8 Scopus citations

Abstract

The aim of this research is to characterize the presence of insulin-degrading enzyme in human colon and ileal mucosal cells. Biochemical studies, including the activity-pH profiles, the effects of enzyme inhibitors, immunoprecipitation and western blots, were conducted. The majority of insulin-degrading activity in colon mucosal cells was localized in the cytosol. In both colon and ileum, cytosolic insulin-degrading activities had a pH optimum at pH 7.5, and were extensively inhibited by each of N-ethylmaleimide, p-chloromercuribenzoate, and 1,10-phenanthroline, but were very weakly affected by each of leupeptin, chymostatin, diisopropyl phosphofluoridate and soybean trypsin inhibitor. In the colon and ileum, more than 93% and 96%, respectively, of cytosolic insulin-degrading activities were removed by the mouse monoclonal antibody to human RBC insulin-degrading enzyme, as compared with less than 20% by the normal mouse IgG for both tissues. Further, a western blot analysis revealed that a cytosolic protein of 110 kD, in both human colon and ileum, reacted with the monoclonal antibody to insulin-degrading enzyme. It is concluded that insulin-degrading enzyme is present in the cytosol of human colon and ileal mucosal cells.

Original languageEnglish (US)
Pages (from-to)1180-1184
Number of pages5
JournalJournal of Pharmacy and Pharmacology
Volume48
Issue number11
DOIs
StatePublished - Jan 1 1996

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