Sodium/proton exchangers (NHEs) are secondary active transporters that catalyze the electroneutral exchange of Na+ and H+ down their respective concentration gradients using the inward electrochemical Na+ gradient established by the plasma membrane Na+ /K+-ATPase. NHEs play a fundamental role in maintaining the intracellular pH (pHi) homeostasis and cell volume which are required for stable protein activity, and ultimately cell survival. To date, nine NHE isoforms (NHE 1-9) have been identified, and are expressed in a tissue/cell specific manner, which indicates a degree of specialization in their respective cellular functions. NHE1 through 5 are plasmalemmal-type exchangers, whereas NHE6 and 7 accumulate predominantly in organellar compartments. Substantially less information is known about NHE8 and NHE9. Initial reports have shown that both NHE8 and NHE9 mRNA are ubiquitously expressed, and that NHE8 protein can be detected in the proximal tubules of kidney nephrons (Goyal et al., 2003; de Silva et al., 2003). / To gain further insight into the subcellular distribution and function of these latter isoforms, full length cDNAs of NHE8 and NHE9 were cloned, epitope tagged and transfected into cultured cell lines. Examination of their subcellular localization by confocal microscopy showed that NHE8 and NHE9 are targeted to lysosomes and endosomes respectively. Furthermore, co-immunoprecipitation experiments indicated that NHE9 can form homodimeric complexes. Co-immunoprecipitation studies and confocal microscopy also indicated that NHE9 may form heterocomplexes with NHE8. In order to further characterize NHE9 under native conditions, a native polyclonal antibody was raised against a distinct region of its C-terminal cytoplasmic tail.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.101147 |
| Date | January 2007 |
| Creators | Jones, Ewen St. Clair. |
| 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 | Master of Science (Department of Physiology.) |
| Rights | © Ewen St. Clair Jones, 2007 |
| Relation | alephsysno: 002588414, proquestno: AAIMR32726, Theses scanned by UMI/ProQuest. |
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