Immunosuppressants implicate protein phosphatase regulation of K+ channels in guard cells

Sheng Luan, Weiwei Li, Frank Rusnak, Sarah Mary Assmann, Stuart L. Schreiber

Research output: Contribution to journalArticle

206 Citations (Scopus)

Abstract

The elevation of Ca2+ levels in the cytoplasm inactivates inward-rectifying K+ channels that play a central role in regulating the apertures of stomatal pores in higher plants. However, the mechanism for the Ca2+-mediated inhibition of K+-channel function is unknown. Using patch-clamp techniques, we show that cyclophilin-cyclosporin A and FK506-binding protein-FK506 complexes, which are highly specific inhibitors of protein phosphatase 2B (calcineurin), block Ca2+-induced inactivation of K+ channels in Vicia faba guard cells. A constitutively active calcineurin fragment that is Ca2+-independent inhibits K+-channel activity in the absence of Ca2+. We have also identified an endogenous Ca2+-dependent phosphatase activity from V. faba that is inhibited by the cyclophilin-cyclosporin A and FK506-binding protein-FK506 complexes. Our findings implicate a Ca2+-dependent, calcineurin-like protein phosphatase in a Ca2+ signal-transduction pathway of higher plants.

Original languageEnglish (US)
Pages (from-to)2202-2206
Number of pages5
JournalProceedings of the National Academy of Sciences of the United States of America
Volume90
Issue number6
DOIs
StatePublished - Mar 15 1993

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Calcineurin
Phosphoprotein Phosphatases
Immunosuppressive Agents
Tacrolimus Binding Proteins
Cyclophilins
Vicia faba
Tacrolimus
Cyclosporine
Patch-Clamp Techniques
Phosphoric Monoester Hydrolases
Signal Transduction
Cytoplasm

All Science Journal Classification (ASJC) codes

  • General

Cite this

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title = "Immunosuppressants implicate protein phosphatase regulation of K+ channels in guard cells",
abstract = "The elevation of Ca2+ levels in the cytoplasm inactivates inward-rectifying K+ channels that play a central role in regulating the apertures of stomatal pores in higher plants. However, the mechanism for the Ca2+-mediated inhibition of K+-channel function is unknown. Using patch-clamp techniques, we show that cyclophilin-cyclosporin A and FK506-binding protein-FK506 complexes, which are highly specific inhibitors of protein phosphatase 2B (calcineurin), block Ca2+-induced inactivation of K+ channels in Vicia faba guard cells. A constitutively active calcineurin fragment that is Ca2+-independent inhibits K+-channel activity in the absence of Ca2+. We have also identified an endogenous Ca2+-dependent phosphatase activity from V. faba that is inhibited by the cyclophilin-cyclosporin A and FK506-binding protein-FK506 complexes. Our findings implicate a Ca2+-dependent, calcineurin-like protein phosphatase in a Ca2+ signal-transduction pathway of higher plants.",
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Immunosuppressants implicate protein phosphatase regulation of K+ channels in guard cells. / Luan, Sheng; Li, Weiwei; Rusnak, Frank; Assmann, Sarah Mary; Schreiber, Stuart L.

In: Proceedings of the National Academy of Sciences of the United States of America, Vol. 90, No. 6, 15.03.1993, p. 2202-2206.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Immunosuppressants implicate protein phosphatase regulation of K+ channels in guard cells

AU - Luan, Sheng

AU - Li, Weiwei

AU - Rusnak, Frank

AU - Assmann, Sarah Mary

AU - Schreiber, Stuart L.

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