title: Polar-localised poplar K+ channel capable of controlling electrical properties of wood-forming cells.
abstract: In previous studies, we have shown that annual expression profiles of cambial and wood tissue with respect to the Shaker K+ channel PTORK correlate with cambial activity. To follow PTORK-gene activity on the cellular level, we isolated the respective promoter regions and generated transgenic Arabidopsis plants expressing the GUS gene under the control of the PTORK promoter. Cross-sections of petioles showed PTORK-driven signals predominantly in the xylem parenchyma surrounding the vessels and in the phloem. Antibodies raised against a unique N-terminal region of PTORK in histo-immunochemical analyses recognised this K+-release channel in growth-active poplar plants only. PTORK labelling was found in differentiating xylem cells (young fibres) and mature xylem (vessel-associated cells of the ray parenchyma). Patch-clamp measurements on fibre cell protoplasts, derived from young poplar twigs, identified outward-rectifying K+ channels as the major K+ conductance of this cell type, which resembled the biophysical properties of PTORK when expressed in Xenopus oocytes.
authors.affiliation: FG Holzbiologie der TU München, Winzererstrasse 45, 80797 Münich, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Arend
authors.forename: Andrea
authors.initials: A
authors.lastname: Stinzing
authors.forename: Christa
authors.initials: C
authors.lastname: Wind
authors.forename: Katharina
authors.initials: K
authors.lastname: Langer
authors.forename: Andreas
authors.initials: A
authors.lastname: Latz
authors.forename: Peter
authors.initials: P
authors.lastname: Ache
authors.forename: Jörg
authors.initials: J
authors.lastname: Fromm
authors.forename: Rainer
authors.initials: R
authors.lastname: Hedrich
mesh_terms: D000595:Amino Acid Sequence; D000906:Antibodies / Q000276:immunology; D017360:Arabidopsis / Q000235:genetics; D004594:Electrophysiology; D005455:Fluorescent Antibody Technique; D015870:Gene Expression; D008969:Molecular Sequence Data; D018408:Patch-Clamp Techniques; D018547:Plant Stems / Q000166:cytology / Q000502:physiology; D030821:Plants, Genetically Modified; D032107:Populus / Q000166:cytology / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D011523:Protoplasts; D051637:Shaker Superfamily of Potassium Channels / Q000032:analysis* / Q000235:genetics; D014934:Wood
chemical_list: D000906:Antibodies; D051637:Shaker Superfamily of Potassium Channels