{"id":4888,"date":"2023-02-17T07:10:24","date_gmt":"2023-02-17T07:10:24","guid":{"rendered":"http:\/\/ionchanneltargets.com\/resource_library\/p2x3-activation-and-inhibition-of-p2x3-channels-recorded-on-the-syncropatch-384pe\/"},"modified":"2023-02-17T07:10:25","modified_gmt":"2023-02-17T07:10:25","slug":"2012-investigation-of-the-sodium-binding-sites-in-the-sodium-coupled-betaine-transporter-betp","status":"publish","type":"resource_library","link":"https:\/\/nanion.com\/zh-hans\/resource_library\/2012-investigation-of-the-sodium-binding-sites-in-the-sodium-coupled-betaine-transporter-betp\/","title":{"rendered":"2012 &#8211; Investigation of the sodium-binding sites in the sodium-coupled betaine transporter BetP"},"content":{"rendered":"<p>Sodium-coupled substrate transport plays a central role in many biological processes. However, despite knowledge of the structures of several sodium-coupled transporters, the location of the sodium-binding site(s) often remains unclear. Several of these structures have the five transmembrane-helix inverted-topology repeat, LeuT-like (FIRL) fold, whose pseudosymmetry has been proposed to facilitate the alternating-access mechanism required for transport. Here, we provide biophysical, biochemical, and computational evidence for the location of the two cation-binding sites in the sodium-coupled betaine symporter BetP. A recent X-ray structure of BetP in a sodium-bound closed state revealed that one of these sites, equivalent to the Na2 site in related transporters, is located between transmembrane helices 1 and 8 of the FIRL-fold; here, we confirm the location of this site by other means. Based on the pseudosymmetry of this fold, we hypothesized that the second site is located between the equivalent helices 6 and 3. Molecular dynamics simulations of the closed-state structure suggest this second sodium site involves two threonine sidechains and a backbone carbonyl from helix 3, a phenylalanine from helix 6, and a water molecule. Mutating the residues proposed to form the two binding sites increased the apparent Km\u00a0and Kd\u00a0for sodium, as measured by betaine uptake, tryptophan fluorescence, and\u00a022Na<sup>+<\/sup>\u00a0binding, and also diminished the transient currents measured in proteoliposomes using solid supported membrane-based electrophysiology. Taken together, these results provide strong evidence for the identity of the residues forming the sodium-binding sites in BetP.<\/p>\n","protected":false},"featured_media":0,"template":"","products_tags":[36],"resource_type":[75],"application_areas":[108],"therapeutic_areas":[],"target_categories":[60],"target_families":[375],"targets":[],"resource_keyword":[],"class_list":["post-4888","resource_library","type-resource_library","status-publish","hentry","products_tags-surfe2r-n1","resource_type-publication","application_areas-transporters","target_categories-transporters","target_families-symporter"],"acf":[],"_links":{"self":[{"href":"https:\/\/nanion.com\/zh-hans\/wp-json\/wp\/v2\/resource_library\/4888","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/nanion.com\/zh-hans\/wp-json\/wp\/v2\/resource_library"}],"about":[{"href":"https:\/\/nanion.com\/zh-hans\/wp-json\/wp\/v2\/types\/resource_library"}],"wp:attachment":[{"href":"https:\/\/nanion.com\/zh-hans\/wp-json\/wp\/v2\/media?parent=4888"}],"wp:term":[{"taxonomy":"products_tags","embeddable":true,"href":"https:\/\/nanion.com\/zh-hans\/wp-json\/wp\/v2\/products_tags?post=4888"},{"taxonomy":"resource_type","embeddable":true,"href":"https:\/\/nanion.com\/zh-hans\/wp-json\/wp\/v2\/resource_type?post=4888"},{"taxonomy":"application_areas","embeddable":true,"href":"https:\/\/nanion.com\/zh-hans\/wp-json\/wp\/v2\/application_areas?post=4888"},{"taxonomy":"therapeutic_areas","embeddable":true,"href":"https:\/\/nanion.com\/zh-hans\/wp-json\/wp\/v2\/therapeutic_areas?post=4888"},{"taxonomy":"target_categories","embeddable":true,"href":"https:\/\/nanion.com\/zh-hans\/wp-json\/wp\/v2\/target_categories?post=4888"},{"taxonomy":"target_families","embeddable":true,"href":"https:\/\/nanion.com\/zh-hans\/wp-json\/wp\/v2\/target_families?post=4888"},{"taxonomy":"targets","embeddable":true,"href":"https:\/\/nanion.com\/zh-hans\/wp-json\/wp\/v2\/targets?post=4888"},{"taxonomy":"resource_keyword","embeddable":true,"href":"https:\/\/nanion.com\/zh-hans\/wp-json\/wp\/v2\/resource_keyword?post=4888"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}