Ion channels constitute a class of proteins that is ultimately responsible for generating and coordinating electrical signals passing through the brain and heart. In order for ion channels to fulfill these roles a number of coordinated events must ensue at the protein level. Newly translated polypeptides entering the endoplasmic reticulum (ER) must be correctly processed and folded in order to exit. In the case of voltage-dependent ion channels, the channel alpha subunits, which form the channel pore, oligomerize with like (or unlike) alpha subunits and/or auxiliary (beta) subunits, depending on the channel type. Further posttranslational modifications take place within the Golgi apparatus before the channels embark for their final destination. Once there, or prior to their arrival, they interact with cytoskeletal elements that serve to anchor the channel in place and tether accessory elements involved in ion channel modulation and signaling. Here, I have investigated the role of N-linked glycosylation in the surface membrane expression of a K+ channel, human ether-a-go-go related gene (HERG), mutation of which can give rise to the cardiac disease long QT. Pharmacological and site-directed mutagenesis reveal that N-linked glycosylation is required for proper channel processing and cell surface expression of HERG as determined through immunoblot, immunocytochemical and electrophysiological analysis. Removal of glycosylation leads to an intracellular retention of HERG. Furthermore, I have examined the subcellular localization of the Na+/H+ exchanger (NHE1 isoform) in cardiomyocytes using immunocytochemical techniques and found that it exhibits a restricted subcellular localization at the intercalated disc. Along the same line, using the yeast two-hybrid screening technique, I have identified an actin-binding protein, filamin, that directly interacts with and plays a role in the subcellular localization of a prominent heart and brain K + channel, Kv4.2.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.36679 |
| Date | January 1999 |
| Creators | Petrecca, Kevin. |
| Contributors | Shrier, Alvin (advisor) |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Doctor of Philosophy (Department of Physiology.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001770805, proquestno: NQ64643, Theses scanned by UMI/ProQuest. |
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