title: Allelic variation in the vacuolar TPK1 channel affects its calcium dependence and may impact on stomatal conductance.
abstract: Natural variation can be exploited to identify allelic variants of proteins. In this study, patch clamp was used to determine transport properties of two AtTPK1 alleles from Landsberg and Kas-2 ecotypes. No difference in conductance or ion selectivity was observed but the Kas version of TPK1 showed different Ca(2+) dependence in its open probability compared to Ler. Leaves from Kas showed lower rates of water loss than those of Ler, in either the absence or presence of ABA, an observation that is consistent with higher TPK1 channel activity at comparable cytoplasmic Ca(2+) concentrations. A model that explains the results is presented.
authors.affiliation: Department of Biology, University of York, UK.
authors.forename: Tom N
authors.initials: TN
authors.lastname: Hartley
authors.affiliation: Department of Biology, University of York, UK.
authors.forename: Frans J M
authors.initials: FJ
authors.lastname: Maathuis
mesh_terms: D000040:Abscisic Acid / Q000494:pharmacology; D000483:Alleles; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000166:cytology / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D020013:Calcium Signaling / Q000187:drug effects; D004553:Electric Conductivity; D056726:Genetic Association Studies; D018527:Hydroponics; D008958:Models, Molecular; D008969:Molecular Sequence Data; D018408:Patch-Clamp Techniques; D010539:Permeability; D010937:Plant Growth Regulators / Q000494:pharmacology; D018515:Plant Leaves / Q000166:cytology / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D054046:Plant Stomata / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D020641:Polymorphism, Single Nucleotide; D015221:Potassium Channels / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D011487:Protein Conformation; D011523:Protoplasts / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D014617:Vacuoles / Q000187:drug effects / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; D010937:Plant Growth Regulators; D015221:Potassium Channels; D011994:Recombinant Proteins; C586033:TPK1 protein, Arabidopsis; D000040:Abscisic Acid
keywords: Arabidopsis; SNP; TPK1; patch clamp; polymorphism; stomata