Characterization of an extended glutamate receptor of the on bipolar neuron in the vertebrate retina.

The synaptic receptors of ON bipolar neurons are selectively activated by 2-amino-4-phosphonobutyrate, a glutamate analogue. This agent uniquely distinguishes these receptors from other types of excitatory amino acid receptors found in the retina. Various glutamate and aspartate analogues were used to assess the structure-activity characteristics of this receptor. The results suggest that it represents one class of glutamate receptor which can be distinguished by its preferential activation by acidic amino acid analogues that match the extended conformation of glutamate.