5hxc
Structural mechanisms of extracellular ion exchange and induced binding-site occlusion in the sodium-calcium exchanger NCX_Mj soaked with 20 mM Na+ and zero Ca2+Structural mechanisms of extracellular ion exchange and induced binding-site occlusion in the sodium-calcium exchanger NCX_Mj soaked with 20 mM Na+ and zero Ca2+
Structural highlights
Publication Abstract from PubMedSodium/calcium (Na(+)/Ca(2+)) exchangers (NCX) are membrane transporters that play an essential role in maintaining the homeostasis of cytosolic Ca(2+) for cell signaling. We demonstrated the Na(+)/Ca(2+)-exchange function of an NCX from Methanococcus jannaschii (NCX_Mj) and report its 1.9 angstrom crystal structure in an outward-facing conformation. Containing 10 transmembrane helices, the two halves of NCX_Mj share a similar structure with opposite orientation. Four ion-binding sites cluster at the center of the protein: one specific for Ca(2+) and three that likely bind Na(+). Two passageways allow for Na(+) and Ca(2+) access to the central ion-binding sites from the extracellular side. Based on the symmetry of NCX_Mj and its ability to catalyze bidirectional ion-exchange reactions, we propose a structure model for the inward-facing NCX_Mj. Structural insight into the ion-exchange mechanism of the sodium/calcium exchanger.,Liao J, Li H, Zeng W, Sauer DB, Belmares R, Jiang Y Science. 2012 Feb 10;335(6069):686-90. PMID:22323814[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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