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dc.contributor.authorLiu, K
dc.contributor.authorSaparov, S M
dc.contributor.authorPohl, P
dc.contributor.authorAgre, P
dc.date.accessioned2010-03-04T20:59:40Z
dc.date.available2010-03-04T20:59:40Z
dc.date.issued2007-02-23
dc.identifier.citationJ Biol Chem. 2007 Feb 23;282(8):5296-301. Epub 2006 Dec 21. doi: 10.1074/jbc.M609343200en_US
dc.identifier.urihttp://jhir.library.jhu.edu/handle/1774.2/33908
dc.description.abstractThe transport of ammonia/ammonium is fundamental to nitrogen metabolism in all forms of life. So far, no clear picture has emerged as to whether a protein channel is capable of transporting exclusively neutral NH(3) while excluding H(+) and NH(4)(+). Our research is the first stoichiometric study to show the selective transport of NH(3) by a membrane channel. The purified water channel protein aquaporin-8 was reconstituted into planar bilayers, and the exclusion of NH(4)(+) or H(+) was established by ensuring a lack of current under voltage clamp conditions. The single channel water permeability coefficient of 1.2 x 10(-14) cm(3)/subunit/s was established by imposing an osmotic gradient across reconstituted planar bilayers, and resulting minute changes in ionic concentration close to the membrane surface were detected. It is more than 2-fold smaller than the single channel ammonia permeability (2.7 x 10(-14) cm(3)/subunit/s) that was derived by establishing a transmembrane ammonium concentration gradient and measuring the resulting concentration increases adjacent to the membrane. This permeability ratio suggests that electrically silent ammonia transport may be the main function of AQP8.en_US
dc.language.isoen_USen_US
dc.publisherAmerican Society for Biochemistry and Molecular Biologyen_US
dc.subjectProtonsen_US
dc.subjectAmmonia/metabolismen_US
dc.subjectLipid Bilayers/metabolismen_US
dc.titleFast and Selective ammonia transport by aquaporin-8en_US
dc.typeArticleen_US


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