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

70 Scopus citations


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
Issue number3
StatePublished - Nov 1994

All Science Journal Classification (ASJC) codes

  • Physiology
  • Genetics
  • Plant Science


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