Ca2+ and nucleotide dependent regulation of voltage dependent anion channels in the plasma membrane of guard cells.
Using the patch-clamp technique we discovered that the voltage dependent anion channels in the plasma membrane of guard cells are activated by a rise in cytoplasmic Ca2+ in the presence of nucleotides. Upon activation, these anion channels catalyse anion currents 10-20 times higher than in the inactivated state, thus shifting the plasma membrane from a K+ conducting state to an anion conducting state. Prolonged stimulation by depolarizing voltages results in the inactivation of the anion current (t1/2 = 10-12 s). We suggest that activation of the anion channel by Ca2+ and nucleotides is a key event in the regulation of salt efflux from guard cells during stomatal closure.
Hedrich
R
R
Pflanzenphysiologisches Institut der Universität, Göttingen, FRG.
Busch
H
H
Raschke
K
K
D000255:Adenosine Triphosphate / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology; D002118:Calcium / Q000494:pharmacology*; D004533:Egtazic Acid / Q000494:pharmacology; D007887:Fabaceae / Q000502:physiology; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000494:pharmacology*; D007473:Ion Channels / Q000187:drug effects / Q000502:physiology*; D008564:Membrane Potentials / Q000187:drug effects; D059828:Plant Cells; D018521:Plant Physiological Phenomena; D010946:Plants, Medicinal; D015221:Potassium Channels / Q000187:drug effects / Q000502:physiology; D011523:Protoplasts / Q000502:physiology
D007473:Ion Channels; D015221:Potassium Channels; C022571:adenosine 5'-O-(3-thiotriphosphate); D016244:Guanosine 5'-O-(3-Thiotriphosphate); D004533:Egtazic Acid; D000255:Adenosine Triphosphate; D002118:Calcium