期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1993
卷号：90
期号：6
页码：2202-2206
DOI：10.1073/pnas.90.6.2202
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：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 Ca(2+)-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 Ca(2+)-induced inactivation of K+ channels in Vicia faba guard cells. A constitutively active calcineurin fragment that is Ca(2+)-independent inhibits K(+)-channel activity in the absence of Ca2+. We have also identified an endogenous Ca(2+)-dependent phosphatase activity from V. faba that is inhibited by the cyclophilin-cyclosporin A and FK506-binding protein-FK506 complexes. Our findings implicate a Ca(2+)-dependent, calcineurin-like protein phosphatase in a Ca2+ signal-transduction pathway of higher plants.
