Evidence for protein phosphatase 1 and 2A regulation of K+ channels in two types of leaf cells

Weiwei Li, Sheng Luan, Stuart L. Schreiber, Sarah M. Assmann

Research output: Contribution to journalArticlepeer-review

68 Scopus citations

Abstract

Ion channels control ion fluxes across membranes, membrane potential, and signal transduction between and within cells. Protein kinases and phosphatases are important regulators involved in stimulus-response coupling in eukaryotic organisms. We have identified in extracts of Vicia faba leaf cells protein phosphatase activities inhibited by okadaic acid (OA) and calyculin A (CA), two inhibitors of protein phosphatases 1 and 2A. Using whole-cell patch-clamp techniques, we have demonstrated that inward K+ currents in guard cells are inhibited by nanomolar concentrations of OA or CA, whereas outward K+ currents are not affected. However, the same inhibitors enhance the magnitude of outward K+ currents in mesophyll cells. A phosphatase antagonist, adenosine-5′-O-(3-thiotriphosphate), has an effect similar to OA and CA on outward K+ currents in mesophyll cells. Our findings suggest that protein phosphatases 1 and/or 2A play different physiological roles in modulating the activity of K+ channels in mesophyll cells and guard cells.

Original languageEnglish (US)
Pages (from-to)963-970
Number of pages8
JournalPlant physiology
Volume106
Issue number3
DOIs
StatePublished - Nov 1994

All Science Journal Classification (ASJC) codes

  • Physiology
  • Genetics
  • Plant Science

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