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Specific interaction of glutamate with membranes from cultured retinal pigment epithelium
Author(s) -
LópezColomé A. M.,
Salceda R.,
Fragoso G.
Publication year - 1993
Publication title -
journal of neuroscience research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.72
H-Index - 160
eISSN - 1097-4547
pISSN - 0360-4012
DOI - 10.1002/jnr.490340410
Subject(s) - glutamate receptor , receptor , biology , nmda receptor , quisqualic acid , glycine , amino acid , taurine , metabotropic glutamate receptor , strychnine , metabotropic receptor , biochemistry , excitatory postsynaptic potential , kainic acid , biophysics , microbiology and biotechnology
Excitatory amino acids (EAA) have been shown to induce phagocytosis in retinal pigment epithelial (RPE) cells. In order to explore if this action is receptor‐mediated, we have identified and characterized receptors for L‐glutamate through the binding of [ 3 H]L‐glutamate to membranes from chick RPE cells in primary culture. Specific binding was found saturable, with K B = 333nM and B max = 3.2 pmol/mg protein in frozen/thawed membranes. Na + ‐independent binding was present in cultures of 16 and 25 days in vitro, and was not affected by temperature. Pharmacological profile of analogues of EAA at different receptor types suggests the presence of a metabotropic type receptor (L‐glutamate > S‐2‐amino‐3‐phosphonopropionate > 2‐amino‐4‐phosphonobutyrate = trans‐(1S,3R)‐1‐aminocyclopentane‐1,3‐dicarboxylate > quisqualate). Excitatory amino acid analogues acting at the NMDA‐receptor also displaced bound L‐glutamate, and a noticeable stimulation of specific binding of this ligand by glycine was shown; this effect was mimicked by D‐serine and 1‐hydroxy‐3‐aminopyrrolidone‐2 (HA‐966) but not by 7‐chlorokynurenate, and was not inhibited by strychnine. Since taurine and GABA also increased specific binding, it is likely that modulation of EAA receptors in RPE differs from that in neurons. © 1993 Wiley‐Liss, Inc.