NCX_Mj - EC50 for Calcium and Magnesium

  SURFE²R N1 data and applications:

Short Description: Na⁺/sugar translocation is detected using a sugar concentration jump in presence of sodium. In absence of sodium, we found a pre steady-state signal, representing sugar binding. Under these conditions, no transport is observed.
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Background and Assay Description: 
We performed a double solution exchange to measure the transport activity of NCX_Mj. The GUVs containing NCX_Mj have been prepared in Na⁺-containing, but Ca²⁺-free solution. The first solution exchange provides a Na+-free solution (Na+ is replaced by K⁺) to establish an outward directed Na⁺ gradient; the second solution exchange provides the divalent cation, either Ca²⁺, Mg²⁺ or Sr²⁺ - to activate the ion exchanger. The resulting current traces show negative amplitude due to the stoichiometry of transport: NCX catalyzes efflux of 3 Na⁺ and influx of 1 divalent cation, reflecting the net charge movement of one positive charge out of the GUVs. By applying different concentrations of one divalent cation on the same sensor, we determined EC₅₀ for Ca²⁺, Mg²⁺ and Sr^2+.

Author: Nanion Technologies
Target: NCX_Mj
Mode of transport: 3Na⁺/Ca²⁺ exchange
Organism: Methanococcus jannaschii
Sample: Reconstituted into Giant Unilamellar Vesicles made of DPhPC
Platform:      SURFE²R N1

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