TY  - JOUR
A1  - Voelker, Camilla
A1  - Gomez-Porras, Judith Lucia
A1  - Becker, Dirk
A1  - Hamamoto, Shin
A1  - Uozumi, Nobuyuki
A1  - Gambale, Franco
A1  - Müller-Röber, Bernd
A1  - Czempinski, Katrin
A1  - Dreyer, Ingo
T1  - Roles of tandem-pore K plus channels in plants : a puzzle still to be solved
N2  - The group of voltage-independent K+ channels in Arabidopsis thaliana consists of six members, five tandem-pore channels (TPK1-TPK5) and a single K-ir-like channel (KCO3). All TPK/KCO channels are located at the vacuolar membrane except for TPK4, which was shown to be a plasma membrane channel in pollen. The vacuolar channels interact with 14-3-3 proteins (also called General Regulating Factors, GRFs), indicating regulation at the level of protein-protein interactions. Here we review current knowledge about these ion channels and their genes, and highlight open questions that need to be urgently addressed in future studies to fully appreciate the physiological functions of these ion channels.
Y1  - 2010
UR  - http://www3.interscience.wiley.com/cgi-bin/issn?DESCRIPTOR=PRINTISSN&VALUE=1435-8603
U6  - https://doi.org/10.1111/j.1438-8677.2010.00353.x
SN  - 1435-8603
ER  - 
TY  - JOUR
A1  - Becker, Dirk
A1  - Geiger, D.
A1  - Dunkel, M.
A1  - Roller, A.
A1  - Bertl, Adam
A1  - Latz, A.
A1  - Carpaneto, Armando
A1  - Dietrich, Peter
A1  - Roelfsema, M. R. G.
A1  - Voelker, C.
A1  - Schmidt, D.
A1  - Müller-Röber, Bernd
A1  - Czempinski, Katrin
A1  - Hedrich, R.
T1  - AtTPK4, an Arabidopsis tandem-pore K+ channel, poised to control the pollen membrane voltage in a pH- and Ca2+- dependent manner
N2  - The Arabidopsis tandem-pore K+ (TPK) channels displaying four transmembrane domains and two pore regions share structural homologies with their animal counterparts of the KCNK family. In contrast to the Shaker-like Arabidopsis channels (six transmembrane domains/one pore region), the functional properties and the biological role of plant TPK channels have not been elucidated yet. Here, we show that AtTPK4 (KCO4) localizes to the plasma membrane and is predominantly expressed in pollen. AtTPK4 (KCO4) resembles the electrical properties of a voltage-independent K+ channel after expression in Xenopus oocytes and yeast. Hyperpolarizing as well as depolarizing membrane voltages elicited instantaneous K+ currents, which were blocked by extracellular calcium and cytoplasmic protons. Functional complementation assays using a K+ transport-deficient yeast confirmed the biophysical and pharmacological properties of the AtTPK4 channel. The features of AtTPK4 point toward a role in potassium homeostasis and membrane voltage control of the growing pollen tube. Thus, AtTPK4 represents a member of plant tandem-pore-K+ channels, resembling the characteristics of its animal counterparts as well as plant-specific features with respect to modulation of channel activity by acidosis and calcium
Y1  - 2004
SN  - 0027-8424
ER  -