Population shift underlies Ca2+-induced regulatory transitions in the sodium-calcium exchanger (NCX)

Abstract

Background: Ca2+ binding to the regulatory two-domain tandem (CBD12) activates ion transport in NCX. Results: Ca2+ binding to high affinity sites of CBD12 results in a population shift, where more constraint conformational states become highly populated. Conclusion: Ca 2+-induced population shift governs NCX activation with no significant contribution of global conformational changes in CBD alignment. Significance: Population shift may represent a general mechanism for regulating NCX. © 2013 by The American Society for Biochemistry and Molecular Biology, Inc.