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Photoaffinity Labelling of Benzodiazepine Receptors: Lack of Effect on Ligand Binding to the Nucleoside Transport System
Author(s) -
Hammond James R.
Publication year - 1985
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1985.tb05564.x
Subject(s) - flunitrazepam , photoaffinity labeling , chemistry , nucleoside , benzodiazepine , allosteric regulation , gabaa receptor , receptor , biochemistry , labelling , ligand (biochemistry) , stereochemistry
This study was undertaken to investigate the possibility of an allosteric interaction between benzodiazepine receptors and the CNS nucleoside transport system. Irreversible (photoaffinity) labelling of the benzodiazepine receptors in guinea pig cortical membranes resulted in a marked reduction in the binding ( B max ) of both [ 3 H]flunitrazepam (71%) and [ 3 H]ethyl‐β‐carboline‐3‐carboxylate (22%) to the benzodiazepine receptors but had no effect on the binding of [ 3 H]nitrobenzylthioinosine to the nucleoside transport system. Furthermore, although photoaffinity labelling resulted in a significant decrease in the affinities of flunitrazepam (∼ 16‐fold) and dipyridamole (∼sevenfold) for the [ 3 H]Ro 15–1788 binding site of the benzodiazepine receptor complex, the affinities of these compounds for the nucleoside transport system were unaltered. These results suggest that the CNS nucleoside transport system and the benzodiazepine receptor complex are distinct, noninteractive ligand recognition sites.