{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,2]],"date-time":"2026-06-02T04:59:56Z","timestamp":1780376396598,"version":"3.54.1"},"reference-count":31,"publisher":"American Physiological Society","issue":"6","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["American Journal of Physiology-Renal Physiology"],"published-print":{"date-parts":[[2003,12]]},"abstract":"<jats:p> One of the defining characteristics of the epithelial sodium channel (ENaC) is its block by the diuretic amiloride. This study investigates the role of the extracellular loop of the \u03b1-subunit of ENaC in amiloride binding and stabilization. Mutations were generated in a region of the extracellular loop, residues 278\u2013283. Deletion of this region, WYRFHY, resulted in a loss of amiloride binding to the channel. Channels formed from wild-type \u03b1-subunits or \u03b1-subunits containing point mutations in this region were examined and compared at the single-channel level. The open probabilities ( P<jats:sub>o<\/jats:sub>) of wild-type channels were distributed into two populations: one with a high P<jats:sub>o<\/jats:sub> and one with a low P<jats:sub>o<\/jats:sub>. The mean open times of all the mutant channels were shorter than the mean open time of the wild-type (high- P<jats:sub>o<\/jats:sub>) channel. Besides mutations Y279A and H282D, which had amiloride binding affinities similar to that of wild-type \u03b1-ENaC, all other mutations in this region caused changes in the amiloride binding affinity of the channels compared with the wild-type channel. These data provide new insight into the relative position of the extracellular loop with respect to the pore of ENaC and its role in amiloride binding and channel gating. <\/jats:p>","DOI":"10.1152\/ajprenal.00094.2003","type":"journal-article","created":{"date-parts":[[2015,3,3]],"date-time":"2015-03-03T20:39:50Z","timestamp":1425415190000},"page":"F1279-F1290","source":"Crossref","is-referenced-by-count":25,"title":["Characterization of an amiloride binding region in the \u03b1-subunit of ENaC"],"prefix":"10.1152","volume":"285","author":[{"given":"Ollie","family":"Kelly","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Chaomei","family":"Lin","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Mohan","family":"Ramkumar","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Nina C.","family":"Saxena","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Thomas R.","family":"Kleyman","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Douglas C.","family":"Eaton","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"24","reference":[{"key":"atypb1","doi-asserted-by":"publisher","DOI":"10.1007\/BF00232519"},{"key":"REF2","doi-asserted-by":"publisher","DOI":"10.1111\/j.1469-7793.1999.00631.x"},{"key":"REF3","doi-asserted-by":"publisher","DOI":"10.1038\/361467a0"},{"key":"atypb2","doi-asserted-by":"publisher","DOI":"10.1152\/ajpcell.1994.267.6.C1682"},{"key":"REF5","doi-asserted-by":"publisher","DOI":"10.1038\/367463a0"},{"key":"REF6","doi-asserted-by":"publisher","DOI":"10.1152\/ajpcell.1996.271.4.C1303"},{"key":"REF7","doi-asserted-by":"publisher","DOI":"10.1007\/978-1-4615-7302-9_7"},{"key":"REF8","doi-asserted-by":"publisher","DOI":"10.1002\/(SICI)1097-0134(199606)25:2<157::AID-PROT2>3.0.CO;2-F"},{"key":"REF9","doi-asserted-by":"publisher","DOI":"10.1016\/S0006-3495(97)78808-8"},{"key":"atypb3","doi-asserted-by":"publisher","DOI":"10.1085\/jgp.111.6.825"},{"key":"REF11","doi-asserted-by":"publisher","DOI":"10.1074\/jbc.271.2.807"},{"key":"REF12","doi-asserted-by":"publisher","DOI":"10.1074\/jbc.272.34.21075"},{"key":"REF13","doi-asserted-by":"crossref","unstructured":"Jain L, Chen XJ, Malik B, Al Khalili O, and Eaton DC. Antisense oligonucleotides against the \u03b1-subunit of ENaC decrease lung epithelial cation-channel activity. Am J Physiol Lung Cell Mol Physiol 276: L1046\u2013L1051, 1999.","DOI":"10.1152\/ajplung.1999.276.6.L1046"},{"key":"REF14","doi-asserted-by":"crossref","unstructured":"Jain L, Chen XJ, Ramosevac S, Brown LA, and Eaton DC. Expression of highly selective sodium channels in alveolar type II cells is determined by culture conditions. Am J Physiol Lung Cell Mol Physiol 280: L646\u2013L658, 2001.","DOI":"10.1152\/ajplung.2001.280.4.L646"},{"key":"REF15","doi-asserted-by":"publisher","DOI":"10.1152\/ajpcell.00610.2001"},{"key":"REF16","doi-asserted-by":"publisher","DOI":"10.1073\/pnas.96.7.4170"},{"key":"REF17","doi-asserted-by":"publisher","DOI":"10.1073\/pnas.94.3.1013"},{"key":"REF18","doi-asserted-by":"publisher","DOI":"10.1152\/ajplung.2000.278.4.L848"},{"key":"REF19","unstructured":"Li XJ, Xu RH, Guggino WB, and Snyder SH. Alternatively spliced forms of the \u03b1-subunit of the epithelial sodium channel: distinct sites for amiloride binding and channel pore. 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