Characterization of a plant glutamate receptor activity.
Bioinformatic approaches have allowed the identification of twenty genes, grouped into three subfamilies, encoding for homologues of animal ionotropic glutamate receptors (iGLRs) in the Arabidopsis thaliana model plant. Indirect evidence suggests that plant iGLRs function as non-selective cation channels. In the present work we provide biochemical and electrophysiological evidences for the chloroplast localization of glutamate receptor(s) of family 3 (iGLR3) in spinach. A specific antibody, recognizing putative receptors of family 3 locates iGLR3 to the inner envelope membrane of chloroplasts. In planar lipid bilayer experiments, purified inner envelope vesicles from spinach display a cation-selective electrophysiological activity which is inhibited by DNQX (6,7-dinitroquinoxaline-2,3-dione), considered to act as an inhibitor on both animal and plant iGLRs. These results identify for the first time the intracellular localization of plant glutamate receptor(s) and a DNQX-sensitive, glutamate-gated activity at single channel level in native membrane with properties compatible with those predicted for plant glutamate receptors.
Teardo
Enrico
E
Department of Biology, University of Padova, Padova, Italy.
Segalla
Anna
A
Formentin
Elide
E
Zanetti
Manuela
M
Marin
Oriano
O
Giacometti
Giorgio Mario
GM
Lo Schiavo
Fiorella
F
Zoratti
Mario
M
Szabò
Ildikò
I
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000378:metabolism; D002736:Chloroplasts / Q000378:metabolism; D008051:Lipid Bilayers / Q000378:metabolism; D010940:Plant Proteins / Q000032:analysis* / Q000037:antagonists & inhibitors / Q000378:metabolism; D011810:Quinoxalines / Q000494:pharmacology; D058468:Receptors, Ionotropic Glutamate / Q000032:analysis* / Q000037:antagonists & inhibitors / Q000378:metabolism; D018724:Spinacia oleracea / Q000378:metabolism
D008051:Lipid Bilayers; D010940:Plant Proteins; D011810:Quinoxalines; D058468:Receptors, Ionotropic Glutamate; C056723:FG 9041