Affinity crosslinking of 125I-human beta-endorphin to cell lines possessing either mu or delta type opioid binding sites.

Affinity crosslinking of human 125I-beta-Endorphin to cell lines possessing either mu or delta binding sites was carried out. Autoradiography of SDS-PAGE gels from these crosslinked cell lines revealed that these two sites contain major peptide subunits that differ in molecular size. This confirms our earlier finding in mammalian brain which demonstrated separate and distinct subunits for mu and delta opioid receptors.