Linked Life Data

18029350

Source:http://linkedlifedata.com/resource/pubmed/id/18029350

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
4
pubmed:dateCreated
2008-1-21
pubmed:databankReference
pubmed:abstractText
The tonoplast K(+) membrane transport system plays a crucial role in maintaining K(+) homeostasis in plant cells. Here, we isolated cDNAs encoding a two-pore K(+) channel (NtTPK1) from Nicotiana tabacum cv. SR1 and cultured BY-2 tobacco cells. Two of the four variants of NtTPK1 contained VHG and GHG instead of the GYG signature sequence in the second pore region. All four products were functional when expressed in the Escherichia coli cell membrane, and NtTPK1 was targeted to the tonoplast in tobacco cells. Two of the three promoter sequences isolated from N. tabacum cv. SR1 were active, and expression from these was increased approximately 2-fold by salt stress or high osmotic shock. To determine the properties of NtTPK1, we enlarged mutant yeast cells with inactivated endogenous tonoplast channels and prepared tonoplasts suitable for patch clamp recording allowing the NtTPK1-related channel conductance to be distinguished from the small endogenous currents. NtTPK1 exhibited strong selectivity for K(+) over Na(+). NtTPK1 activity was sensitive to spermidine and spermine, which were shown to be present in tobacco cells. NtTPK1 was active in the absence of Ca(2+), but a cytosolic concentration of 45 microM Ca(2+) resulted in a 2-fold increase in the amplitude of the K(+) current. Acidification of the cytosol to pH 5.5 also markedly increased NtTPK1-mediated K(+) currents. These results show that NtTPK1 is a novel tonoplast K(+) channel belonging to a different group from the previously characterized vacuolar channels SV, FV, and VK.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jan
pubmed:issn
0021-9258
pubmed:author
pubmed:issnType
Print
pubmed:day
25
pubmed:volume
283
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
1911-20
pubmed:dateRevised
2008-11-21
pubmed:meshHeading
pubmed-meshheading:18029350-Amino Acid Sequence, pubmed-meshheading:18029350-Calcium, pubmed-meshheading:18029350-Cell Membrane, pubmed-meshheading:18029350-Escherichia coli, pubmed-meshheading:18029350-Gene Expression Regulation, Plant, pubmed-meshheading:18029350-Homeostasis, pubmed-meshheading:18029350-Hydrogen-Ion Concentration, pubmed-meshheading:18029350-Ion Transport, pubmed-meshheading:18029350-Molecular Sequence Data, pubmed-meshheading:18029350-Osmotic Pressure, pubmed-meshheading:18029350-Patch-Clamp Techniques, pubmed-meshheading:18029350-Plant Proteins, pubmed-meshheading:18029350-Potassium, pubmed-meshheading:18029350-Potassium Channels, pubmed-meshheading:18029350-Promoter Regions, Genetic, pubmed-meshheading:18029350-Recombinant Proteins, pubmed-meshheading:18029350-Saccharomyces cerevisiae, pubmed-meshheading:18029350-Sodium, pubmed-meshheading:18029350-Tobacco, pubmed-meshheading:18029350-Vacuoles
pubmed:year
2008
pubmed:articleTitle
Characterization of a tobacco TPK-type K+ channel as a novel tonoplast K+ channel using yeast tonoplasts.
pubmed:affiliation
Department of Biomolecular Engineering, Graduate School of Engineering, Tohoku University, Aobayama 6-6-07, Sendai 980-8579, Japan.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't