Open AccessA rice high-affinity potassium transporter (HKT) conceals a calcium-permeable cation channel
Author(s) -
Wenzhi Lan,
Wei Wang,
Suo-Min Wang,
Legong Li,
Bob B. Buchanan,
Hong-Xuan Lin,
Jinliang Gao,
Sheng Luan
Publication year - 2010
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.1000698107
Subject(s) - divalent , symporter , potassium , transporter , sodium , chemistry , biochemistry , calcium , function (biology) , biophysics , microbiology and biotechnology , biology , gene , organic chemistry
Planth igh-affinityK+ t ransport (HKT) proteins are so named because of their relation to bacterial and fungal transporters that mediate high-affinity K+ uptake. The view that HKT family members are sodium-selective uniporters or sodium-potassium symporters is widely held. We have found that one of the rice HKT proteins also functions as a Ca2+ -permeable cation channel that conducts current carried by a wide range of monovalent and divalent cations. TheHKT rice gene, namedOsHKT2;4 , is expressed in several cell types, including root hairs and vascular parenchyma cells. The protein is localized to the plasma membrane, thereby providing a mechanism for cation uptake and extrusion. This finding goes against firmly entrenched dogma in showing that HKT proteins can function as both ion carriers and channels. The study further extends the function of HKT proteins to Ca2+ -linked processes and, in so doing, defines a previously undescribed type of Ca2+ -permeable cation channels in plants. The work also raises questions about the evolutionary changes in this protein family following the divergence of monocots and dicots.