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'''Crystal structure of the Na+/H+ antiporter NhaA''' | '''Crystal structure of the Na+/H+ antiporter NhaA''' | ||
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[[Category: Screpanti, E.]] | [[Category: Screpanti, E.]] | ||
[[Category: Venturi, M.]] | [[Category: Venturi, M.]] | ||
[[Category: | [[Category: Antiporter]] | ||
[[Category: | [[Category: Membrane protein]] | ||
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 17:27:29 2008'' | |||
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Revision as of 14:27, 3 May 2008
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 Page seeded by OCA on Sat May 3 17:27:29 2008
