NCX1: mechanism of transport

Adv Exp Med Biol. 2013:961:49-54. doi: 10.1007/978-1-4614-4756-6_5.

Abstract

The plasma membrane Na(+)/Ca(2+) exchanger (NCX) plays a critical role in the maintenance of Ca(2+) homeostasis in a variety of tissues. NCX accomplishes this task by either lowering or increasing the intracellular Ca(2+) concentration, a process which depends on electrochemical gradients. During each cycle, three Na(+) are transported in the opposite direction to one Ca(2+), resulting in an electrogenic transport that can be measured as an ionic current.The residues involved in ion translocation are unknown. A residue thought to be important for Na(+) and/or Ca(2+) transport, Ser(110), was replaced with a cysteine, and the properties of the resulting exchanger mutant were analyzed using the giant patch technique. Data indicate that this residue, located in transmembrane segment 2 (part of the α-1 repeat), is important for both Na(+) and Ca(2+) translocations. Using cysteine susceptibility analysis, we demonstrated that Ser(110) is exposed to the cytoplasm when the exchanger is in the inward state configuration.

Publication types

  • Review

MeSH terms

  • Animals
  • Calcium* / chemistry
  • Calcium* / metabolism
  • Homeostasis / physiology*
  • Humans
  • Ion Transport / physiology
  • Mutation
  • Protein Structure, Secondary
  • Sodium* / chemistry
  • Sodium* / metabolism
  • Sodium-Calcium Exchanger / chemistry*
  • Sodium-Calcium Exchanger / genetics
  • Sodium-Calcium Exchanger / metabolism*

Substances

  • Sodium-Calcium Exchanger
  • sodium-calcium exchanger 1
  • Sodium
  • Calcium