Evidence for heterogenous glycine domains but conserved multiple states of the excitatory amino acid recognition site of the NMDA receptor: regional binding studies with [3H]glycine and [3H]L-glutamate.

Abstract

The possible heterogeneity of the agonist and glycine sites of the N-methyl-D-aspartate (NMDA) receptor-complex was examined using receptor binding techniques. Binding of [3H]L-glutamate [( 3H]GLU) and [3H]glycine to synaptic membranes of cerebral and cerebellar cortices, and membranes of a granule cell preparation of rat cerebellum, was characterized. [3H]Glycine always labelled a single population of sites; densities of binding sites (Bmax) in cortical, cerebellar and "granule" membranes were 3.1, 0.87 and 3.6 pmol/mg protein, respectively. Dissociation constants (Kd) in the same three preparations were 0.13, 0.31 and 1.9 microM, respectively. In competition studies, D-cycloserine, but not..