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: R G Hammonds Jr, M Westphal, C H Li
• Journal: Biochemical and biophysical research communications (Biochem Biophys Res Commun) Vol. 128 Issue 3 Pg. 1310-4 (May 16 1985) ISSN: 0006-291X [Print] United States
• PMID: 2988533 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't, Research Support, U.S. Gov't, P.H.S.)

Chemical References

• Affinity Labels
• Azides
• Endorphins
• Receptors, Opioid
• beta-Endorphin
• 2-nitro-4-azidophenylsulfenyl chloride

Topics

• Affinity Labels
• Azides
• Binding Sites
• Cell Line
• Endorphins (metabolism)
• Humans
• Molecular Weight
• Neuroblastoma (metabolism)
• Receptors, Opioid (metabolism)
• beta-Endorphin