Characterization of a glutamic acid neurotransmitter binding site on neuroblastoma hybrid cells.

摘要: Glutamate is thought to be a major excitatory neurotransmitter in the central nervous system. To study glutamate receptor and its regulation under carefully controlled conditions, specific binding of [3H]glutamate was characterized washed membranes isolated from neuroblastoma X retina hybrid cell line, N18-RE-105. [3H]Glutamate bound saturable reversible fashion with an apparent dissociation constant, KD, 650 nM maximum capacity, Bmax, 16 pmol/mg protein. Pharmacologic characterization site indicates that it closely resembles Na+-independent for found on brain amino acid receptor. Thus, while kainate, N-methyl-DL-aspartate, nonamino ligands did not displace [3H]glutamate, quisqualate ibotenate were potent inhibitors binding. Furthermore, this regulated by ions manner which described hippocampus (Baudry, M., Lynch, G. (1979) Nature (Lond.) 282, 748-750). Calcium (10 mM) increased number sites 2.6-fold no change receptor-ligand affinity. Lanthanum (1 only other cation added enhanced (3-fold) [3H]glutamate. Monovalent cations resulted decrease sites. Incubation presence chloride caused marked [3H] binding, effect synergistic calcium incubation. N18-RE-105 cells possess pharmacologically similar exhibits regulatory properties resembling those previously hippocampal membranes, providing excellent model mechanistic studies.