title: Guard cell-specific calcium sensitivity of high density and activity SV/TPC1 channels.
abstract: The slow vacuolar (SV) channel, a Ca2+-regulated vacuolar cation conductance channel, in Arabidopsis thaliana is encoded by the single-copy gene AtTPC1. Although loss-of-function tpc1 mutants were reported to exhibit a stoma phenotype, knowledge about the underlying guard cell-specific features of SV/TPC1 channels is still lacking. Here we demonstrate that TPC1 transcripts and SV current density in guard cells were much more pronounced than in mesophyll cells. Furthermore, the SV channel in motor cells exhibited a higher cytosolic Ca2+ sensitivity than in mesophyll cells. These distinct features of the guard cell SV channel therefore probably account for the published stomatal phenotype of tpc1-2.
authors.affiliation: University of Wuerzburg, Institute for Molecular Plant Physiology and Biophysics, Julius-von-Sachs Platz 2, D-97082 Wuerzburg, Germany.
authors.forename: Florian
authors.initials: F
authors.lastname: Rienmüller
authors.forename: Diana
authors.initials: D
authors.lastname: Beyhl
authors.forename: Silke
authors.initials: S
authors.lastname: Lautner
authors.forename: Jörg
authors.initials: J
authors.lastname: Fromm
authors.forename: Khaled A S
authors.initials: KA
authors.lastname: Al-Rasheid
authors.forename: Peter
authors.initials: P
authors.lastname: Ache
authors.forename: Edward E
authors.initials: EE
authors.lastname: Farmer
authors.forename: Irene
authors.initials: I
authors.lastname: Marten
authors.forename: Rainer
authors.initials: R
authors.lastname: Hedrich
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000235:genetics / Q000378:metabolism*; D055724:Electrophysiological Phenomena; D058503:Mesophyll Cells / Q000378:metabolism; D009154:Mutation; D018408:Patch-Clamp Techniques; D018515:Plant Leaves / Q000737:chemistry; D054046:Plant Stomata / Q000378:metabolism*; D011188:Potassium / Q000032:analysis; D012964:Sodium / Q000032:analysis; D013312:Stress, Physiological; D014617:Vacuoles / Q000378:metabolism*; D000097903:Two-Pore Channels
chemical_list: D029681:Arabidopsis Proteins; D002118:Calcium; D015220:Calcium Channels; D011188:Potassium; D012964:Sodium; C498240:TPC1 protein, Arabidopsis; D000097903:Two-Pore Channels