caa a22 4500 477101232 CHVBK 20180405111542.0 cr unu---uuuuu 170330e19960201xx s 000 0 eng 10.1007/BF00206254 doi (NATIONALLICENCE)springer-10.1007/BF00206254 Inositol 1,4,5-trisphosphate may mediate closure of K+ channels by light and darkness in Samanea saman motor cells [Elektronische Daten] [Hak Kim, Gary Coté, Richard Crain] Leaflet movements of Samanea saman (Jacq.) Merr. depend in part upon circadian-rhythmic, light-regulated K+ fluxes across the plasma membranes of extensor and flexor cells in opposing regions of the leaf-moving organ, the pulvinus. We previously showed that blue light appears to close open K+ channels in flexor protoplasts during the dark period (subjective night) (Kim et al., 1992, Plant Physiol 99: 1532-1539). In contrast, transfer to darkness apparently closes open K+ channels in extensor protoplasts during the light period (subjective day) (Kim et al., 1993, Science 260: 960-962). We now report that both these channel-closing stimuli increase inositol 1,4,5-trisphosphate [Ins(1,4,5)P3] levels in the appropriate protoplasts. If extensor cells are given a pulse of red light followed by transfer to darkness, channels still apparently close (Kim et al. 1993) but changes in Ins(1,4,5)P3 levels are complex with an initial decrease under red light followed by accumulation. Neomycin, an inhibitor of polyphosphoinositide hydrolysis, inhibits both blue-light-induced Ins(1,4,5)P3 production and K+-channel closure in flexor protoplasts and both dark-induced Ins(1,4,5)P3 production and K+ channel closure in extensor protoplasts. The G-protein activator, mastoparan, mimics blue light and darkness in that it both increases Ins(1,4,5)P3 levels and closes K+ channels in the appropriate cell type at the appropriate time. These results indicate that phospholipase C-catalyzed hydrolysis of phosphoinositides, possibly activated by a G protein, is an early step in the signal-transduction pathway by which blue light and darkness close K+ channels in S. saman pulvinar cells. Springer-Verlag, 1996 Inositol 1,4,5-trisphosphate nationallicence K+ Channel nationallicence Leaf movement nationallicence Phototransduction nationallicence Samanea (K+ channels) nationallicence Turgor regulation nationallicence DiS-C3-(5) : 3,3′-dipropylthiadicarbocyanine iodide nationallicence ΔF : measure change in Dis-C3-(5) fluorescence nationallicence Fo : initial Dis-C3-(5) fluorescence nationallicence Ins(1,4,5)P3 : inositol 1,4,5-trisphosphate nationallicence PtdIns(4,5)P2 : phosphatidylinositol 4,5-bisphosphate nationallicence rbc : red blood cell nationallicence Kim Hak U-125, Department of Molecular and Cell Biology, The University of Connecticut, 06269-3125, Storrs, CT, USA aut Coté Gary U-125, Department of Molecular and Cell Biology, The University of Connecticut, 06269-3125, Storrs, CT, USA aut Crain Richard U-125, Department of Molecular and Cell Biology, The University of Connecticut, 06269-3125, Storrs, CT, USA aut Planta Springer-Verlag 198/2(1996-02-01), 279-287 0032-0935 198:2<279 1996 198 425 https://doi.org/10.1007/BF00206254 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF00206254 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Kim Hak U-125, Department of Molecular and Cell Biology, The University of Connecticut, 06269-3125, Storrs, CT, USA aut NATIONALLICENCE 700 1- Coté Gary U-125, Department of Molecular and Cell Biology, The University of Connecticut, 06269-3125, Storrs, CT, USA aut NATIONALLICENCE 700 1- Crain Richard U-125, Department of Molecular and Cell Biology, The University of Connecticut, 06269-3125, Storrs, CT, USA aut NATIONALLICENCE 773 0- Planta Springer-Verlag 198/2(1996-02-01), 279-287 0032-0935 198:2<279 1996 198 425 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer