Structural and Functional Analysis of Intracellular Loop 5 of the NHE1 Isoform of the Na+/H+ Exchanger

  • Author / Creator
    Wong, Ka Yee
  • The mammalian Na+/H+ exchanger isoform 1 (NHE1) is an integral membrane protein that regulates intracellular pH. It removes a single intracellular proton in exchange for one extracellular sodium ion. It has a large 500 amino acid N-terminal membrane domain that mediates transport and consists of 12 transmembrane segments with several membrane-associated segments including intracellular and extracellular loops. Extracellular regions of this domain are believed to contribute to sodium coordination. Intracellular loops may coordinate protons and modulate the sensitivity to intracellular pH. In this study we characterized the structure and function of intracellular loop 5 (IL5) amino acids Gly431-Lys443. Mutation of eleven residues to alanine caused partial inhibition of transport; notably, mutation of residues R440A and I436A, demonstrated that these residues were critical for NHE1 function. The structure of a peptide of IL5 revealed that it is unstructured in DMSO, however in sodium dodecyl sulfate solution it possessed significant alpha helical character. A significant finding was that Lys438 was in close proximity with Trp434 residue. Overall our results show that IL5 is a critical intracellular loop, with a propensity to form an alpha helix, with many residues being critical for proton transport.

  • Subjects / Keywords
  • Graduation date
    Fall 2017
  • Type of Item
  • Degree
    Master of Science
  • DOI
  • License
    This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.
  • Language
  • Institution
    University of Alberta
  • Degree level
  • Department
  • Supervisor / co-supervisor and their department(s)
  • Examining committee members and their departments
    • McKay, Ryan T. (Chemistry)
    • Young, Howard (Biochemistry)
    • Sykes, Brian D. (Biochemistry)
    • Cordat, Emmanuelle (Physiology)