The world's first wiki where authorship really matters (Nature Genetics, 2008). Due credit and reputation for authors. Imagine a global collaborative knowledge base for original thoughts. Search thousands of articles and collaborate with scientists around the globe.

wikigene or wiki gene protein drug chemical gene disease author authorship tracking collaborative publishing evolutionary knowledge reputation system wiki2.0 global collaboration genes proteins drugs chemicals diseases compound
Hoffmann, R. A wiki for the life sciences where authorship matters. Nature Genetics (2008)
 
 
 
 
 

Glycine residues in potassium channel-like selectivity filters determine potassium selectivity in four-loop-per-subunit HKT transporters from plants.

Plant HKT proteins comprise a family of cation transporters together with prokaryotic KtrB, TrkH, and KdpA transporter subunits and fungal Trk proteins. These transporters contain four loop domains in one polypeptide with a proposed distant homology to K(+) channel selectivity filters. Functional expression in yeast and Xenopus oocytes revealed that wheat HKT1 mediates Na(+)-coupled K(+) transport. Arabidopsis AtHKT1, however, transports only Na(+) in eukaryotic expression systems. To understand the molecular basis of this difference we constructed a series of AtHKT1/HKT1 chimeras and introduced point mutations to AtHKT1 and wheat HKT1 at positions predicted to be critical for K(+) selectivity. A single-point mutation, Ser-68 to glycine, was sufficient to restore K(+) permeability to AtHKT1. The reverse mutation in HKT1, Gly-91 to serine, abrogated K(+) permeability. This glycine in P-loop A of AtHKT1 and HKT1 can be modeled as the first glycine of the K(+) channel selectivity filter GYG motif. The importance of such filter glycines for K(+) selectivity was confirmed by interconversion of Ser-88 and Gly-88 in the rice paralogues OsHKT1 and OsHKT2. Surprisingly, all HKT homologues known from dicots have a serine at the filter position in P-loop A, suggesting that these proteins function mainly as Na(+) transporters in plants and that Na(+)/K(+) symport in HKT proteins is associated with a glycine in the filter residue. These data provide experimental evidence that the glycine residues in selectivity filters of HKT proteins are structurally related to those of K(+) channels.[1]

References

  1. Glycine residues in potassium channel-like selectivity filters determine potassium selectivity in four-loop-per-subunit HKT transporters from plants. Mäser, P., Hosoo, Y., Goshima, S., Horie, T., Eckelman, B., Yamada, K., Yoshida, K., Bakker, E.P., Shinmyo, A., Oiki, S., Schroeder, J.I., Uozumi, N. Proc. Natl. Acad. Sci. U.S.A. (2002) [Pubmed]
 
WikiGenes - Universities