Fast and Selective ammonia transport by aquaporin-8
| dc.contributor.author | Liu, Kun | |
| dc.contributor.author | Saparov, Sapar M. | |
| dc.contributor.author | Pohl, Peter | |
| dc.contributor.author | Agre, Peter | |
| dc.date.accessioned | 2010-03-04T20:59:40Z | |
| dc.date.available | 2010-03-04T20:59:40Z | |
| dc.date.issued | 2007-02-23 | |
| 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_US |
| dc.identifier.citation | J Biol Chem. 2007 Feb 23;282(8):5296-301. Epub 2006 Dec 21. doi: 10.1074/jbc.M609343200 | en_US |
| dc.identifier.uri | http://jhir.library.jhu.edu/handle/1774.2/33908 | |
| dc.language.iso | en_US | en_US |
| dc.publisher | American Society for Biochemistry and Molecular Biology | en_US |
| dc.subject | Protons | en_US |
| dc.subject | Ammonia/metabolism | en_US |
| dc.subject | Lipid Bilayers/metabolism | en_US |
| dc.title | Fast and Selective ammonia transport by aquaporin-8 | en_US |
| dc.type | Article | en_US |