Identification of the serotonin-S2 receptor ligand binding site by photoaffinity labelling with 7-azido-8-[125I]ketanserin ([125I]AZIK).
7-Azido-8-[125I]ketanserin ([125I]AZIK) was characterized as a potent photoaffinity probe for serotonin-S2 receptors. In reversible binding experiments, [125I]AZIK bound with high affinity (Kd = 0.69 nM) to rat frontal cortex membranes. When incubation with [125I]AZIK was followed by UV irradiation, the binding was found to be irreversible. Protection experiments with various drugs demonstrated the serotonin-S2 nature of the photoaffinity labelling. SDS-polyacrylamide gel electrophoresis of the photolabelled membranes allowed one to identify the serotonin-S2 receptor ligand binding site as a single polypeptide with a molecular mass of approx. 67,500 Da. [125I]AZIK will be a valuable tool for the elucidation of the serotonin-S2 receptor structure.
D000345:Affinity Labels; D000818:Animals; D001386:Azides / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D005625:Frontal Lobe / Q000378:metabolism*; D007650:Ketanserin / Q000031:analogs & derivatives* / Q000378:metabolism; D008970:Molecular Weight; D010777:Photochemistry; D051381:Rats; D011919:Rats, Inbred Strains; D011985:Receptors, Serotonin / Q000378:metabolism*
D000345:Affinity Labels; D001386:Azides; D011985:Receptors, Serotonin; C044880:7-azidoketanserin; D007650:Ketanserin