Crucial to the function of polarized epithelial cells is the generation and maintenance of distinct protein populations at the apical and basolateral domains. Cellular mechanisms sustain this polarity by properly sorting apical and basolateral proteins in both the biosynthetic and postendocytic pathways via sorting signals inherent within the protein. N-glycosylation has been specifically implicated as one of several sorting signals responsible for delivery of proteins to the apical surface along the biosynthetic pathway. Whether this sorting signal is also used along the postendocytic pathway is currently not known. To examine N-glycan-dependent trafficking along the biosynthetic pathway and explore a possible role for N-glycans in sorting along the postendocytic pathway, this study focuses on the sialomucin endolyn. Characterization of the biosynthetic sorting signal revealed that two glycans at amino acid positions 68 and 74 were necessary and sufficient for apical delivery of endolyn. Terminal processing of N-glycans is also necessary for efficient apical delivery as incubation with kifunensine, a drug that inhibits terminal processing of N-glycans, resulted in the nonpolarized delivery of endolyn. A similar N-glycan-dependent sorting signal was also found to be important for apical recycling of endolyn along the postendocytic pathway. The use of the same sorting signal suggested that endolyn may be sorted in a compartment that is common to both the biosynthetic and postendocytic pathway. However, further studies revealed that endolyn is sorted in distinct compartments along these two pathways. These data enhance our understanding of how and where N-glycans mediate apical sorting to maintain the integrity of polarized sorting in epithelial cells.
| Identifer | oai:union.ndltd.org:PITT/oai:PITTETD:etd-10022006-135959 |
| Date | 09 October 2006 |
| Creators | Potter, Beth Ann |
| Contributors | Dr. Ora Weisz, Dr. Martin Schmidt, Dr. Paul Kinchington, Dr. Rebecca Hughey, Dr. Gerard Apodaca |
| Publisher | University of Pittsburgh |
| Source Sets | University of Pittsburgh |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.library.pitt.edu/ETD/available/etd-10022006-135959/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to University of Pittsburgh or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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