title: Beta-endorphin: photoaffinity labelling of a non-opioid binding site in a human neuroblastoma.
abstract: A photoaffinity reagent 2-nitro-4-azidophenylsulfenyl chloride (2,4-NAPS-Cl) and synthetic analogs of human beta-endorphin (beta h-EP) were employed to demonstrate the presence of receptor sites specific for beta h-EP but of non-opioid character in a human neuroblastoma cell line (IMR-32). The radioactive photoaffinity probe was carried out using [125I-Tyr1,2,4-NAPS-Trp27]-beta h-EP and IMR-32 cell membranes. After solubilization with sodium dodecyl sulfate (SDS) and SDS polyacrylamide gel electrophoresis, a single labelled protein band was identified with a molecular weight of 72,000. Labelling was blocked by beta h-EP or beta h-EP-(6-31) but remained in the presence of beta h-EP-(1-27). The specificity of this band is thus identical to that of the non-opioid site previously characterized. Various nonionic or zwitterionic detergents did not extract the labelled non-opioid site.
authors.forename: R G
authors.initials: RG
authors.lastname: Hammonds
authors.forename: M
authors.initials: M
authors.lastname: Westphal
authors.forename: C H
authors.initials: CH
authors.lastname: Li
mesh_terms: D000345:Affinity Labels; D001386:Azides; D001665:Binding Sites; D002460:Cell Line; D004723:Endorphins / Q000378:metabolism*; D006801:Humans; D008970:Molecular Weight; D009447:Neuroblastoma / Q000378:metabolism*; D011957:Receptors, Opioid / Q000378:metabolism; D001615:beta-Endorphin
chemical_list: D000345:Affinity Labels; D001386:Azides; D004723:Endorphins; D011957:Receptors, Opioid; D001615:beta-Endorphin; C027146:2-nitro-4-azidophenylsulfenyl chloride