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  • 标题:Unmasking of magnesium-dependent high-affinity binding sites for [dAla2, dLeu5]enkephalin after pretreatment of brain membranes with guanine nucleotides
  • 本地全文:下载
  • 作者:K J Chang ; S G Blanchard ; P Cuatrecasas
  • 期刊名称:Proceedings of the National Academy of Sciences
  • 印刷版ISSN:0027-8424
  • 电子版ISSN:1091-6490
  • 出版年度:1983
  • 卷号:80
  • 期号:4
  • 页码:940-944
  • DOI:10.1073/pnas.80.4.940
  • 语种:English
  • 出版社:The National Academy of Sciences of the United States of America
  • 摘要:The regulation of mu- and delta-opiate receptors by guanine nucleotides and cations was studied by examining the binding of [3H][DAla2, DLeu5]enkephalin to rat brain membranes. The binding to mu-opiate receptors could be suppressed by 1 microM [DPro4]morphiceptin, a highly specific mu-agonist, thus permitting separate assessment of delta-opiate receptor binding. GTP, GDP, and the nonhydrolyzable analogs 5'-guanylyl imidodiphosphate (Gpp[NH]p) and guanosine 5'-O-(2-thiodiphosphate) (GDP-S) effectively decreased the binding to both receptor types. This inhibitory effect was potentiated by Na+. The inhibitory effect of GTP and GDP, but not of the nonhydrolyzable analogs, was reversed by Mg2+. Pretreatment of membranes with GDP or GTP increased substantially the subsequently measured high-affinity binding, and this effect required the presence of Mg2+ in the binding assay. Similar pretreatment with GDP-S resulted in only a partial increase of binding compared to GTP or GDP, and Gpp[NH]p was relatively ineffective. Similar results were observed for both mu- and delta-receptors, although the effects on mu-receptors were quantitatively more profound. These data suggest that guanine nucleotides play a dual function in regulating opiate receptor binding in a manner dependent upon the presence of Na+ or Mg2+.
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