A transient outward-rectifying K+ channel current down-regulated by cytosolic Ca2+ in Arabidopsis thaliana guard cells

Journal Article (Journal Article)

Sustained (noninactivating) outward-rectifying K channel currents have been identified in a variety of plant cell types and species. Here, in Arabidopsis thaliana guard cells, in addition to these sustained K currents, an inactivating outward-rectifying K current was characterized (plant A-type current: I ). I activated rapidly with a time constant of 165 ms and inactivated slowly with a time constant of 7.2 sec at +40 mV. I was enhanced by increasing the duration (from 0 to 20 sec) and degree (from +20 to -100 mV) of prepulse hyperpolarization. Ionic substitution and relaxation (tail) current recordings showed that outward I was mainly carried by K ions. In contrast to the sustained outward-rectifying K currents, cytosolic alkaline pH was found to inhibit I and extracellular K was required for I activity. Furthermore, increasing cytosolic free Ca in the physiological range strongly inhibited I activity with a half inhibitory concentration of ≈ 94 nM. We present a detailed characterization of an inactivating K current in a higher plant cell. Regulation of I by diverse factors including membrane potential, cytosolic Ca and pH, and extracellular K and Ca implies that the inactivating I described here may have important functions during transient depolarizations found in guard cells, and in integrated signal transduction processes during stomatal movements. + + + + + + 2+ + 2+ + 2+ AP AP AP AP AP AP AP AP AP

Full Text

Duke Authors

Cited Authors

  • Pei, ZM; Baizabal-Aguirre, VM; Allen, GJ; Schroeder, JI

Published Date

  • May 26, 1998

Published In

Volume / Issue

  • 95 / 11

Start / End Page

  • 6548 - 6553

International Standard Serial Number (ISSN)

  • 0027-8424

Digital Object Identifier (DOI)

  • 10.1073/pnas.95.11.6548

Citation Source

  • Scopus