B. Ribalet

Bykova

Hilge

Hilgemann

J. N. Weiss

Johnson

K. D. Philipson

Kimura

Levitsky

M. Ottolia

Matsuoka

OTTOLIA

Ottolia

Patton

PHILIPSON

S. A. John

Sitte

Stryer

Van Munster

Wolber

Zacharias

Cytoplasmic Ca
 2+
 is known to regulate Na
 +
 –Ca
 2+
 exchanger (NCX) activity by binding to two adjacent Ca
 2+
 -binding domains (CBD1 and CBD2) located in the large intracellular loop between transmembrane segments 5 and 6. We investigated Ca
 2+
 -dependent movements as changes in FRET between exchanger proteins tagged with CFP or YFP at position 266 within the large cytoplasmic loop. Data indicate that the exchanger assembles as a dimer in the plasma membrane. Addition of Ca
 2+
 decreases the distance between the cytoplasmic loops of NCX pairs. The Ca
 2+
 -dependent movements detected between paired NCXs were abolished by mutating the Ca
 2+
 coordination sites in CBD1 (D421A, E451A, and D500V), whereas disruption of the primary Ca
 2+
 coordination site in CBD2 (E516L) had no effect. Thus, the Ca
 2+
 -induced conformational changes of NCX dimers arise from the movement of CBD1. FRET studies of CBD1, CBD2, and CBD1–CBD2 peptides displayed Ca
 2+
 -dependent movements with different apparent affinities. CBD1–CBD2 showed a Ca
 2+
 -dependent phenotype mirroring full-length NCX but distinct from both CBD1 and CBD2.
 </jats:p

Scott A. John

Bernard Ribalet

James N. Weiss

Kenneth D. Philipson

Michela Ottolia

Crossref

Proceedings of the National Academy of Sciences

Ca
 2
 +
 -dependent structural rearrangements within Na
 +
 –Ca
 2+
 exchanger dimers

Ca2+-dependent structural rearrangements within Na+-Ca2+ exchanger dimers

Ca2+-dependent structural rearrangements within Na+-Ca2+ exchanger dimers

Abstract

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