A rat brain opioid receptor protein was isolated by binding [∈-biotinyl-Lys32]β-endorphin to membranes, solubilizing the receptor-ligand (R·L) complex with deoxycholate-lysophosphatidylcholine and purifying on immobilized streptavidin and wheat germ agglutinin. The purified glycoprotein had a molecular mass of 60-70 kDa. Recovery of this protein was blocked by the non-selective opioid antagonist naloxone and the highly μ-selective agonist [D-Ala2,N-methyl-Phe4,Glyol5]-enkephalin but not by the highly δ-selective agonist [D-Pen2,4′-Cl-Phe4,D-Pen5]enkephalin when these compounds were added as competitors at the binding step. The 60-70-kDa receptor protein co-purified through the streptavidin column with 40-kDa protein recognized by anti-Giα antibodies. GTP and Na+ influenced dissociation of the solubilized R·125I-L complex and elution of the receptor and G protein from streptavidin in fashions consistent with the pharmacology of μ-opioid receptors. A 23-amino acid residue sequence from the purified receptor differs at 4 positions from a similar sequence in the murine δ-opioid receptor and is encoded within a novel rat brain cDNA isolated by polymerase chain reaction with oligonucleotide primers related to the murine δ-opioid receptor gene.
|Original language||English (US)|
|Number of pages||5|
|Journal||Journal of Biological Chemistry|
|State||Published - Dec 15 1993|
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