Publications [#230050] of Zhen-Ming Pei
search www.ncbi.nlm.nih.gov.Papers Published
- Pei, ZM; Baizabal-Aguirre, VM; Allen, GJ; Schroeder, JI, A transient outward-rectifying K+ channel current down-regulated by cytosolic Ca2+ in Arabidopsis thaliana guard cells,
Proceedings of the National Academy of Sciences of the United States of America, vol. 95 no. 11
(May, 1998),
pp. 6548-6553, Proceedings of the National Academy of Sciences [pdf], [doi] .
(last updated on 2024/08/25)Abstract:
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: IAP). IAP activated rapidly with a time constant of 165 ms and inactivated slowly with a time constant of 7.2 sec at +40 mV. IAP 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 IAP was mainly carried by K+ ions. In contrast to the sustained outward-rectifying K+ currents, cytosolic alkaline pH was found to inhibit IAP and extracellular K+ was required for IAP activity. Furthermore, increasing cytosolic free Ca2+ in the physiological range strongly inhibited IAP 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 IAP by diverse factors including membrane potential, cytosolic Ca2+ and pH, and extracellular K+ and Ca2+ implies that the inactivating IAP described here may have important functions during transient depolarizations found in guard cells, and in integrated signal transduction processes during stomatal movements.