Affinity purification of the opioid receptor in NG 108‐15 cells using an avidin‐biotin system with a novel elution method

Abstract
Affinity purification of the opioid receptor in NG 108‐15 cells was carried out using an affinity resin based on the avidin‐biotin interactions, but a new elution method was employed with a radioligand of sub‐micromolar concentration. A synthesized biotinyl derivative of leucine‐enkephalin has a high affinity for the δ‐receptor, but the affinity was lowered 10‐fold in the presence of avidin. The new elution method is based on this affinity decrease and resulted in a 100‐fold purification over the initial crude materials in the single step. SDS‐polyacrylamide gel electrophoresis of the purified receptor revealed three polypeptides of 58, 65 and 71 kDa as possible components of the δ‐receptor.