Opioid binding properties of the purified kappa receptor from human placenta

Mahmoud S. Ahmed, De he Zhou, Anna G. Cavinato, Dev Maulik

Research output: Contribution to journalArticlepeer-review

33 Scopus citations


A glycoprotein with a molecular weight of 63,000 has been purified, in an active form, from human placental villus tissue membranes. The binding properties of this glycoprotein to opioid alkaloids and peptides indicates that it is the kappa opiate receptor of human placenta. The receptor binds the tritiated ligands etorphine, bremazocine, ethylketocyclazocine and naloxone specifically and reversibly with Kd values of 3.3, 4.4, 5.1 and 7.0nM, respectively. The binding of 3H-Bremazocine to the purified receptor is inhibited by the following compounds with the corresponding Ki values EKC, 1.3×10-8M; Dynorphin 1-8, 3.03×10-7; U50,488H, 4.48×10-9; U69-593, 2.28×10-8, morphine, 4.05×10-6 DADLE, 6.47×10-6 and naloxone, 2.64×10-8. The purified receptor binds 8 nmole of 3H-Etorphine and 1.7 nmole 3H-BZC per mg protein. The theoretical binding capacity of a protein of this molecular weight is 15.8. Although the iodinated purified receptor appears by autoradiography as one band on SDS-PAGE, yet homogeneity of the preparation is not claimed.

Original languageEnglish (US)
Pages (from-to)861-871
Number of pages11
JournalLife Sciences
Issue number13
StatePublished - 1989
Externally publishedYes

ASJC Scopus subject areas

  • General Pharmacology, Toxicology and Pharmaceutics
  • General Biochemistry, Genetics and Molecular Biology


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