In animal brains, ionotropic glutamate receptors (GluRs) function as glutamate-activated ion channels in rapid synaptic transmission. We have now discovered that genes encoding putative ionotropic GluRs exist in plants, and we present preliminary evidence for their involvement in light-signal transduction. It may be that signalling between cells by excitatory amino acids in animal brains evolved from a primitive signalling mechanism that existed before the divergence of plants and animals. Our findings also help to explain why neuroactive compounds made by plants work on receptors in human brains.

1. The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong
2. Department of Biology, New York University, 1009 Main Building, 100 Washington Square East, New York, New York 10003, USA
   e-mail: Email: coruzg01@mcrcr.med.nyu.edu