Glutamate Receptors

Ionotropic glutamate receptors (iGluRs) in animals are channels that conduct K+, Na+, and Ca2+ into the postsynaptic cell after binding the neurotransmitter glutamate (1). Arabidopsis possesses 20 genes homologous to iGluRs (2) and displays ionic responses to glutamate similar to those caused by iGluR activation in neurons (3). Comparative electrophysiological studies of wild-type and glr mutant plants have shown that at least some plant glutamate receptors (GLRs) act as ion channels through which Ca2+ enters the cytoplasm after activation by six very different extracellular amino acids (ala, asn, cys, glu, gly, and ser) and the tri-peptide glutathione (4,5). The present overarching hypothesis is that the large amount of carbon exuded from plant roots and deposited in soils from decaying organic matter (6) includes GLR agonists that influence plant growth and behavior through Ca2+ signaling. Within the context of this hypothesis, the activity, structure, and localization of GLR molecules are being studied with biophysical, molecular, and cell biological techniques.

The Department of Energy funds this work.


animal and plant glutamate receptor cartoon

 

Edgar Spalding

Spalding Lab

Rat iGluR structure

This image was taken from the breakthrough article of Sobolevsky AI, Rosconi MP, Gouaux E (2009) X-ray structure, symmetry and mechanism of an AMPA-subtype glutamate receptor. Nature 462: 745-756.