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

Barthmes, Maria; Liao, Jun; Jiang, Youxing; Brüggemann, Andrea und Wahl-Schott, Christian (2016): Electrophysiological characterization of the archaeal transporter NCX_Mj using solid supported membrane technology. In: Journal of General Physiology, Bd. 147, Nr. 6: S. 485-496

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.

• Dokumententyp: Zeitschriftenartikel
• Fakultät: Chemie und Pharmazie > Department für Pharmazie - Zentrum für Pharmaforschung
• Themengebiete: 500 Naturwissenschaften und Mathematik > 540 Chemie
• ISSN: 0022-1295
• Sprache: Englisch