This Article Full Text Full Text (PDF) Purchase Article View Shopping Cart Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Copyright Permission Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Chesneau, V. Articles by Rosner, M. R. Search for Related Content PubMed PubMed Citation Articles by Chesneau, V. Articles by Rosner, M. R.

Insulin-Degrading Enzyme Does Not Require Peroxisomal Localization for Insulin Degradation¹

Ben May Institute for Cancer Research (V.C., R.K.P., M.R.R.), The University of Chicago, Chicago, Illinois 60637; Department of Pharmacology (W.L., G.-A.K.), Genetech, Inc., San Francisco, California 94080; Columbia University College of Physicians and Surgeons (R.K.P.), New York, New York 10032

Address all correspondence and requests for reprints to: Marsha Rich Rosner, Ben May Institute for Cancer Research, University of Chicago, 5841 South Maryland Avenue, MC 6027, Chicago, Illinois 60637. E-mail: mrosner{at}ben-may.bsd.uchicago.edu

Although considerable evidence implicates insulin-degrading enzyme (IDE) in the cellular metabolism of insulin in many cell types, its mechanism and site of action are not clear. In this study, we have examined the relationship between insulin-degrading enzyme’s peroxisomal location and its ability to degrade insulin by mutation of its peroxisomal targeting signal (PTS), the carboxy terminal A/S-K-L tripeptide. Site-directed mutagenesis was used to destroy the peroxisomal targeting signal of human insulin-degrading enzyme by changing alanine to leucine (AL.pts), leucine to valine (LV.pts), or by deleting the entire tripeptide (DEL.pts). The alanine or leucine mutants, when expressed in COS cells, were indistinguishable from wild-type insulin-degrading enzyme with respect to size (110 kDa), amount of immunoreactive material, ability to bind insulin, in vitro activity, and cellular degradation of insulin. In contrast, the deletion mutant was shorter in size (0 kDa) and unable to bind the hormone. Thus, although the tripeptide at insulin-degrading enzyme’s carboxy terminus appeared to confer enzyme stability, the conserved sequence was not required for insulin degradation. Finally, an immunocytofluorescence study showed that, whereas a significant amount of the wild-type protein was localized in peroxisomes, none of the peroxisomal targeting mutants could be detected in these organelles. These findings indicate that insulin-degrading enzyme does not require peroxisomal localization for insulin degradation and suggest that this enzyme has multiple cellular functions.

This article has been cited by other articles:

				K. Vekrellis, Z. Ye, W. Q. Qiu, D. Walsh, D. Hartley, V. Chesneau, M. R. Rosner, and D. J. Selkoe Neurons Regulate Extracellular Levels of Amyloid beta -Protein via Proteolysis by Insulin-Degrading Enzyme J. Neurosci., March 1, 2000; 20(5): 1657 - 1665. [Abstract] [Full Text] [PDF]

				W. Q. Qiu, D. M. Walsh, Z. Ye, K. Vekrellis, J. Zhang, M. B. Podlisny, M. R. Rosner, A. Safavi, L. B. Hersh, and D. J. Selkoe Insulin-degrading Enzyme Regulates Extracellular Levels of Amyloid beta -Protein by Degradation J. Biol. Chem., December 4, 1998; 273(49): 32730 - 32738. [Abstract] [Full Text] [PDF]

				W. C. Duckworth, R. G. Bennett, and F. G. Hamel Insulin Degradation: Progress and Potential Endocr. Rev., October 1, 1998; 19(5): 608 - 624. [Abstract] [Full Text]