19 ビオチン化プローブを用いた細胞表層のアブシジン酸受容部位の定量的解析

概要

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Abscisic acid (ABA) has been shown as a stress hormone to regulate plant water relations under drought by closing stomata. Though ion channel regulation by ABA has been studied as a model system for plant signal transduction, molecular identification as well as cellular localization of ABA receptor(S) has not yet been clarified. We synthesized biotin-labeled ABA (bioABA) and examined ABA binding sites on the surface of stomatal guard cells. bioABA had similar effects on stomatal closing and shrinking of guard cell protoplasts (GCPs). ABA binding sites were visualized by fluorescence microscopy and confocal laser scanning microscopy (CLSM), using bioABA and fluorescence-labeled avidin. Fluorescent particles were observed on the surface of GCPs in patches. We have developed flow cytometry (FCM) of GCPs, which demonstrated substantial specific binding of bioABA. Fluorescence was quantified by FCM as well as CLSM. Binding of bioABA was inhibited by non-labeled ABA in a dose-dependent manner. Pretreatment of GCPs with proteinase K also impaired the binding of bioABA. These results suggest the presence of ABA perception sites on the surface of stomatal guard cells. Experiments using ABA analogs as well as ABA perception sites in other tissues or species will also be discussed.
植物化学調節学会の論文
2002-10-31