1zcd
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(New page: 200px<br /><applet load="1zcd" size="450" color="white" frame="true" align="right" spinBox="true" caption="1zcd, resolution 3.45Å" /> '''Crystal structure of...)
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Revision as of 05:15, 21 November 2007
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Crystal structure of the Na+/H+ antiporter NhaA
Overview
The control by Na+/H+ antiporters of sodium/proton concentration and cell, volume is crucial for the viability of all cells. Adaptation to high, salinity and/or extreme pH in plants and bacteria or in human heart, muscles requires the action of Na+/H+ antiporters. Their activity is, tightly controlled by pH. Here we present the crystal structure of, pH-downregulated NhaA, the main antiporter of Escherichia coli and many, enterobacteria. A negatively charged ion funnel opens to the cytoplasm and, ends in the middle of the membrane at the putative ion-binding site., There, a unique assembly of two pairs of short helices connected by, crossed, extended chains creates a balanced electrostatic environment. We, propose that the binding of charged substrates causes an electric, imbalance, inducing movements, that permit a rapid alternating-access, mechanism. This ion-exchange machinery is regulated by a conformational, change elicited by a pH signal perceived at the entry to the cytoplasmic, funnel.
About this Structure
1ZCD is a Single protein structure of sequence from Escherichia coli. Full crystallographic information is available from OCA.
Reference
Structure of a Na+/H+ antiporter and insights into mechanism of action and regulation by pH., Hunte C, Screpanti E, Venturi M, Rimon A, Padan E, Michel H, Nature. 2005 Jun 30;435(7046):1197-202. PMID:15988517
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