{"id":4858,"date":"2023-02-17T07:10:21","date_gmt":"2023-02-17T07:10:21","guid":{"rendered":"http:\/\/ionchanneltargets.com\/resource_library\/hclc-1-characterization-of-hclc-1-on-the-syncropatch-384\/"},"modified":"2023-02-17T07:10:21","modified_gmt":"2023-02-17T07:10:21","slug":"2011-transport-mechanism-and-ph-regulation-of-the-na-h-antiporter-nhaa-from-escherichia-coli","status":"publish","type":"resource_library","link":"https:\/\/nanion.com\/ja\/resource_library\/2011-transport-mechanism-and-ph-regulation-of-the-na-h-antiporter-nhaa-from-escherichia-coli\/","title":{"rendered":"2011 &#8211; Transport Mechanism and pH Regulation of the Na<sup>+<\/sup>\/H+ Antiporter NhaA from Escherichia coli"},"content":{"rendered":"<p>Using an electrophysiological assay the activity of NhaA was tested in a wide pH range from pH 5.0 to 9.5. Forward and reverse transport directions were investigated at zero membrane potential using preparations with inside-out and right side-out-oriented transporters with Na<sup>+<\/sup>\u00a0or H+\u00a0gradients as the driving force. Under symmetrical pH conditions with a Na<sup>+<\/sup>\u00a0gradient for activation, both the wt and the pH-shifted G338S variant exhibit highly symmetrical transport activity with bell-shaped pH dependences, but the optimal pH was shifted 1.8 pH units to the acidic range in the variant. In both strains the pH dependence was associated with a systematic increase of the Km\u00a0for Na<sup>+<\/sup>\u00a0at acidic pH. Under symmetrical Na<sup>+<\/sup>\u00a0concentration with a pH gradient for NhaA activation, an unexpected novel characteristic of the antiporter was revealed; rather than being down-regulated, it remained active even at pH as low as 5. These data allowed a transport mechanism to advance based on competing Na<sup>+<\/sup>\u00a0and H+\u00a0binding to a common transport site and a kinetic model to develop quantitatively explaining the experimental results. In support of these results, both alkaline pH and Na<sup>+<\/sup>\u00a0induced the conformational change of NhaA associated with NhaA cation translocation as demonstrated here by trypsin digestion. Furthermore, Na<sup>+<\/sup>\u00a0translocation was found to be associated with the displacement of a negative charge. In conclusion, the electrophysiological assay allows the revelation of the mechanism of NhaA antiport and sheds new light on the concept of NhaA pH regulation.<\/p>\n","protected":false},"featured_media":0,"template":"","products_tags":[36],"resource_type":[75],"application_areas":[108],"therapeutic_areas":[],"target_categories":[60],"target_families":[],"targets":[],"resource_keyword":[],"class_list":["post-4858","resource_library","type-resource_library","status-publish","hentry","products_tags-surfe2r-n1","resource_type-publication","application_areas-transporters","target_categories-transporters"],"acf":[],"_links":{"self":[{"href":"https:\/\/nanion.com\/ja\/wp-json\/wp\/v2\/resource_library\/4858","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/nanion.com\/ja\/wp-json\/wp\/v2\/resource_library"}],"about":[{"href":"https:\/\/nanion.com\/ja\/wp-json\/wp\/v2\/types\/resource_library"}],"wp:attachment":[{"href":"https:\/\/nanion.com\/ja\/wp-json\/wp\/v2\/media?parent=4858"}],"wp:term":[{"taxonomy":"products_tags","embeddable":true,"href":"https:\/\/nanion.com\/ja\/wp-json\/wp\/v2\/products_tags?post=4858"},{"taxonomy":"resource_type","embeddable":true,"href":"https:\/\/nanion.com\/ja\/wp-json\/wp\/v2\/resource_type?post=4858"},{"taxonomy":"application_areas","embeddable":true,"href":"https:\/\/nanion.com\/ja\/wp-json\/wp\/v2\/application_areas?post=4858"},{"taxonomy":"therapeutic_areas","embeddable":true,"href":"https:\/\/nanion.com\/ja\/wp-json\/wp\/v2\/therapeutic_areas?post=4858"},{"taxonomy":"target_categories","embeddable":true,"href":"https:\/\/nanion.com\/ja\/wp-json\/wp\/v2\/target_categories?post=4858"},{"taxonomy":"target_families","embeddable":true,"href":"https:\/\/nanion.com\/ja\/wp-json\/wp\/v2\/target_families?post=4858"},{"taxonomy":"targets","embeddable":true,"href":"https:\/\/nanion.com\/ja\/wp-json\/wp\/v2\/targets?post=4858"},{"taxonomy":"resource_keyword","embeddable":true,"href":"https:\/\/nanion.com\/ja\/wp-json\/wp\/v2\/resource_keyword?post=4858"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}