[3H]Propyl-6-azido-β-carboline-3-carboxylate: a new photoaffinity label for the GABAA-benzodiazepine receptor

Abstract [ 3 H]Propyl-6-azido-β-carboline-3-carboxylate ([ 3 H]ACCP) exhibited a high affinity for GABA A receptors affinity purified from the brains of adult rats, and binding of this compound could be inhibited by several ligands of the benzodiazepine binding site of GABA A receptors. On irradiation with UV light, [ 3 H]ACCP, similarly to [ 3 H]flunitrazepam, irreversibly labeled a protein with an apparent molecular weight of 51 kDa in affinity-purified GABA A receptors, and this labeling could be inhibited in the presence of diazepam. These data indicate that [ 3 H]ACCP can be used as a photoaffinity label for GABA A receptors.