Oocytes from Xenopus laevis contain an intrinsic σ2-like binding site

Terrell A. Patterson, Mark Connor, Suzanne M. Appleyard, Charles Chavkin*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

3 Citations (Scopus)


In preparation for expression studies for rat brain σ-binding sites, Xenopus oocytes were tested for the presence of [3H]di-o-tolylguanidine (DTG)-binding sites. Native oocytes were found to contain two intrinsic [3H]DTG-binding sites, a high-affinity site (Kd = 32 ± 6 nM, Bmax of 45.7 ± 19 pmol/mg protein) and a low-affinity binding site (Kd = 1.3 ± 0.7 μM, Bmax of 3.2 ± 0.7 nmol/mg protein). In a series of radioligand-binding-displacement studies, the high-affinity binding sites were found to have a binding profile which has a similar Kd to that of the mammalian σ2-binding site (32 vs. 38 nM). Comparison of the IC50 values for inhibition of [3H]DTG binding in rat liver and oocytes for DTG, haloperidol (HAL), (-)-pentazocine, (+)-3-(3-hydroxyphenyl)-N-propylpiperidine hydrochloride ((+)-3-PPP), (+(-pentazocine and Zn2+, showed similarity in rank (r2 = 0.913) but a 7-fold lower potency in oocytes. These results suggest that the high-affinity [3H]DTG-binding site in oocytes represents a σ2-like binding site.

Original languageEnglish
Pages (from-to)159-162
Number of pages4
JournalNeuroscience Letters
Issue number2
Publication statusPublished - 24 Oct 1994
Externally publishedYes


  • di-o-Tolylguanidine
  • Haloperidol
  • Pentazocine
  • Xenopus oocyte
  • σ-Binding site
  • σ-Receptor


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