Home | Help | Feedback | Subscriptions | Archive | Search | Table of Contents

This Article Full Text Full Text (PDF, 3638K) PDF+supp data (5620K) PPT slides of all figures Supplemental Material Index Alert me when this article is cited Citation Map Services Email this article Similar articles in this journal Similar articles in PubMed Alert me to new content in the JCB Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Glozman, R. Articles by Lukacs, G. L. Search for Related Content PubMed PubMed Citation Articles by Glozman, R. Articles by Lukacs, G. L. Social Bookmarking                            What's this?

N-glycans are direct determinants of CFTR folding and stability in secretory and endocytic membrane traffic

¹ Hospital for Sick Children Research Institute, ² Department of Molecular Genetics, and ³ Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada M5G 1X8
⁴ Department of Physiology, McGill University, Montreal, Quebec, Canada H3G 1Y6

Correspondence to Gergely L. Lukacs: gergely.lukacs{at}mcgill.ca

N-glycosylation, a common cotranslational modification, is thought to be critical for plasma membrane expression of glycoproteins by enhancing protein folding, trafficking, and stability through targeting them to the ER folding cycles via lectin-like chaperones. In this study, we show that N-glycans, specifically core glycans, enhance the productive folding and conformational stability of a polytopic membrane protein, the cystic fibrosis transmembrane conductance regulator (CFTR), independently of lectin-like chaperones. Defective N-glycosylation reduces cell surface expression by impairing both early secretory and endocytic traffic of CFTR. Conformational destabilization of the glycan-deficient CFTR induces ubiquitination, leading to rapid elimination from the cell surface. Ubiquitinated CFTR is directed to lysosomal degradation instead of endocytic recycling in early endosomes mediated by ubiquitin-binding endosomal sorting complex required for transport (ESCRT) adaptors Hrs (hepatocyte growth factor–regulated tyrosine kinase substrate) and TSG101. These results suggest that cotranslational N-glycosylation can exert a chaperone-independent profolding change in the energetic of CFTR in vivo as well as outline a paradigm for the peripheral trafficking defect of membrane proteins with impaired glycosylation.

Abbreviations used in this paper: Ab, antibody; BFA, brefeldin A; CAS, castanospermine; CF, cystic fibrosis; CFTR, CF transmembrane conductance regulator; CHX, cycloheximide; CNX, calnexin; CRT, calreticulin; ELAD, endolysosomal degradation; endo, endoglycosidase; ERAD, ER-associated degradation; ESCRT, endosomal sorting complex required for transport; FRIA, fluorescence ratiometric image analysis; LSB, Laemmli sample buffer; MVB, multivesicular body; pH_v, vesicular pH; PNGase, peptide N-glycosidase; TUN, tunicamycin; Ub, ubiquitin; WGA, wheat germ agglutinine; wt, wild type.

© 2009 Glozman et al.
This article is distributed under the terms of an Attribution–Noncommercial–Share Alike–No Mirror Sites license for the first six months after the publication date (see http://www.jcb.org/misc/terms.shtml). After six months it is available under a Creative Commons License (Attribution–Noncommercial–Share Alike 3.0 Unported license, as described at http://creativecommons.org/licenses/by-nc-sa/3.0/).

CiteULike

Complore

Connotea

Del.icio.us

Digg

Facebook

Reddit

Technorati

Twitter

This article has been cited by other articles:

• Barriere, H., Bagdany, M., Bossard, F., Okiyoneda, T., Wojewodka, G., Gruenert, D., Radzioch, D., Lukacs, G. L. (2009). Revisiting the Role of Cystic Fibrosis Transmembrane Conductance Regulator and Counterion Permeability in the pH Regulation of Endocytic Organelles. Mol. Biol. Cell 20: 3125-3141 [Abstract] [Full Text]  

Home | Help | Feedback | Subscriptions | Archive | Search | Table of Contents