1279120

Evidence that high- and low-affinity DL-alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) binding sites reflect membrane-dependent states of a single receptor.

Article date: 1992/12/1

PubMed ID: 1279120

Journal name: Journal of neurochemistry (ISSN: 0022-3042)

ABSTRACT

Binding of DL-alpha-[3H]amino-3-hydroxy-5-methyl-isoxazole-4-propionic acid ([3H]AMPA) to lysed rat brain membranes in the presence of potassium thiocyanate resulted in curvilinear Scatchard plots that could be resolved by regression analysis into a large low-affinity component and a small high-affinity component. Solubilization with Triton X-100 resulted in solubilized and nonsolubilized fractions that were considerably enriched in the high-affinity component and correspondingly reduced in the low-affinity component. It thus appears that solubilization converts low-affinity AMPA receptors into high-affinity receptors. Also, synaptic plasma membranes were found to be greatly enriched in the low-affinity form and deficient in the high-affinity form of the AMPA receptor. These experiments provide evidence for the hypothesis that the high- and low-affinity components of AMPA binding are interconvertible states of the same receptor rather than separate binding sites and that the conversion of these receptors from their native high-affinity state to the low-affinity state occurs on insertion of the receptors into synapses.

Author List: Hall R A, Kessler M, Lynch G

Publication Types: Journal Article; Research Support, U.S. Gov't, Non-P.H.S.; Research Support, U.S. Gov't, P.H.S.

Substances mentioned in the article: Receptors, AMPA; Receptors, Glutamate; Ibotenic Acid; Polyethylene Glycols; alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid; Octoxynol;

Mesh terms: Animals; Binding Sites; Brain/ultrastructure; Ibotenic Acid/analogs & derivatives; Male; Octoxynol; Polyethylene Glycols; Protein Binding; Rats; Rats, Sprague-Dawley; Receptors, AMPA; Receptors, Glutamate/analysis; Solubility; Synaptic Membranes/chemistry; alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid;

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