Fast and Selective ammonia transport by aquaporin-8

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dc.contributor.author Liu, K
dc.contributor.author Saparov, S M
dc.contributor.author Pohl, P
dc.contributor.author Agre, P
dc.date.accessioned 2010-03-04T20:59:40Z
dc.date.available 2010-03-04T20:59:40Z
dc.date.issued 2007-02-23
dc.identifier.citation J Biol Chem. 2007 Feb 23;282(8):5296-301. Epub 2006 Dec 21. doi: 10.1074/jbc.M609343200 en
dc.identifier.uri http://jhir.library.jhu.edu/handle/1774.2/33908
dc.description.abstract The 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
dc.description.provenance Approved for entry into archive by David Reynolds(davidr@jhu.edu) on 2010-03-04T20:59:40Z (GMT) No. of bitstreams: 1 J. Biol. Chem.-2007-Saparov-5296-301.pdf: 1554832 bytes, checksum: 0fbb4438fd3c4bb68033a65b463e7bd1 (MD5) en
dc.description.provenance Submitted by Janice Chen (janice.chen@jhu.edu) on 2010-02-26T19:23:30Z No. of bitstreams: 1 J. Biol. Chem.-2007-Saparov-5296-301.pdf: 1554832 bytes, checksum: 0fbb4438fd3c4bb68033a65b463e7bd1 (MD5) en
dc.description.provenance Made available in DSpace on 2010-03-04T20:59:40Z (GMT). No. of bitstreams: 1 J. Biol. Chem.-2007-Saparov-5296-301.pdf: 1554832 bytes, checksum: 0fbb4438fd3c4bb68033a65b463e7bd1 (MD5) Previous issue date: 2007-02-23 en
dc.language.iso en_US en
dc.publisher American Society for Biochemistry and Molecular Biology en
dc.subject Protons en
dc.subject Ammonia/metabolism en
dc.subject Lipid Bilayers/metabolism en
dc.title Fast and Selective ammonia transport by aquaporin-8 en
dc.type Article en

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