Electrophysiological characterization of the archaeal transporter NCX_Mj using solid supported membrane technology

Maria Barthmes, Jun Liao, Youxing Jiang, Andrea Brüggemann, Christian Wahl-Schott

Research output: Contribution to journalArticle

5 Scopus citations

Abstract

Sodium-calcium exchangers (NCXs) are membrane transporters that play an important role in Ca2+ homeostasis and Ca2+ signaling. The recent crystal structure of NCX_Mj, a member of the NCX family from the archaebacterium Methanococcus jannaschii, provided insight into the atomistic details of sodium-calcium exchange. Here, we extend these findings by providing detailed functional data on purified NCX_Mj using solid supported membrane (SSM)-based electrophysiology, a powerful but unexploited tool for functional studies of electrogenic transporter proteins. We show that NCX_Mj is highly selective for Na+, whereas Ca2+ can be replaced by Mg2+ and Sr2+ and that NCX_Mj can be inhibited by divalent ions, particularly Cd2+. By directly comparing the apparent affinities of Na+ and Ca2+ for NCX_Mj with those for human NCX1, we show excellent agreement, indicating a strong functional similarity between NCX_Mj and its eukaryotic isoforms. We also provide detailed instructions to facilitate the adaption of this method to other electrogenic transporter proteins. Our findings demonstrate that NCX_Mj can serve as a model for the NCX family and highlight several possible applications for SSM-based electrophysiology.

Original languageEnglish (US)
Pages (from-to)485-496
Number of pages12
JournalJournal of General Physiology
Volume147
Issue number6
DOIs
Publication statusPublished - 2016

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ASJC Scopus subject areas

  • Physiology

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