PT  - JOURNAL ARTICLE
AU  - Nathan E. Thomas
AU  - Katherine A. Henzler-Wildman
TI  - Unlocking the Reversal Potential of Solid Supported Membrane Electrophysiology to Determine Transport Stoichiometry
AID  - 10.1101/2020.05.07.082438
DP  - 2020 Jan 01
TA  - bioRxiv
PG  - 2020.05.07.082438
4099  - http://biorxiv.org/content/early/2020/05/07/2020.05.07.082438.short
4100  - http://biorxiv.org/content/early/2020/05/07/2020.05.07.082438.full
AB  - Transport stoichiometry provides insight into the mechanism and function of ion-coupled transporters, but measuring transport stoichiometry is time-consuming and technically difficult. With the increasing evidence that many ion-coupled transporters employ multiple transport stoichiometries under different conditions, improved methods to determine transport stoichiometry are required to accurately characterize transporter activity. Reversal potential was previously shown to be a reliable, general method for determining the transport stoichiometry of ion-coupled transporters (Fitzgerald & Mindell, 2017). Here, we develop a new technique for measuring transport stoichiometry with greatly improved throughput using solid supported membrane electrophysiology (SSME). Using this technique, we are able to verify the recent report of a fixed 2:1 stoichiometry for the proton:guanidinium antiporter Gdx. Our SSME method requires only small amounts of transporter and provides a fast, easy, general method for measuring transport stoichiometry, which will facilitate future mechanistic and functional studies of ion-coupled transporters.