Structural Biology

Maintaining Equilibrium

Sci. Signal.  14 Feb 2012:
Vol. 5, Issue 211, pp. ec49
DOI: 10.1126/scisignal.2002949

Na+/Ca2+ exchangers (NCX) are membrane transporters that maintain the homeostasis of cytosolic Ca2+ and play an essential role in Ca2+ signaling. Despite a long history of physiological work and a large body of functional data, the structural basis underlying the ion exchange mechanism of NCX is poorly understood. Liao et al. (see the Perspective by Abramson et al.) present a high-resolution crystal structure of an NCX from Methanococcus jannaschii and demonstrate that this archaeal NCX catalyzes Na+/Ca2+-exchange reactions similar to its eukaryotic counterpart. The structure clarifies the mechanism of ion exchange proteins and reveals the basis for the stoichiometry, cooperativity, and bidirectionality of the reaction.

J. Liao, H. Li, W. Zeng, D. B. Sauer, R. Belmares, Y. Jiang, Structural insight into the ion-exchange mechanism of the sodium/calcium exchanger. Science 335, 686–690 (2012). [Abstract] [Full Text]

J. Abramson, A. Paz, K. D. Philipson, It's all in the symmetry. Science 335, 669–670 (2012). [Abstract] [Full Text]