title: Guanine nucleotide regulation of [125I]beta-endorphin binding to NG108-15 and SK-N-SH cell membranes: specific cation requirements.
abstract: Regulation of [125I]beta h-endorphin binding by guanine nucleotides was investigated in membrane preparations from two opioid receptor-containing cell lines: NG108-15, which contains only delta opioid receptors, and SK-N-SH, which contains predominantly mu opioid receptors. In contrast to the binding of the delta-selective agonist [3H][D-penicillamine2,D-penicillamine5]enkephalin to NG108-15 cell membranes, and of the mu-selective agonist [3H][D-Ala2,MePhe4,Gly-ol5]enkephalin to SK-N-SH cell membranes, [125I]beta h-endorphin binding to NG108-15 and SK-N-SH cell membranes was not altered by guanosine triphosphate (GTP) or guanylyl-5'-imidodiphosphate (Gpp(NH)p) in the absence of cations. However, in the presence of NaCl, [125I]beta h-endorphin binding to both cell lines was inhibited by GTP and Gpp(NH)p in a concentration-dependent manner. In SK-N-SH cell membranes, the ability of sodium to promote regulation of [125I]beta h-endorphin binding by GTP was mimicked by the monovalent cations lithium and potassium, but not by the divalent cations magnesium, calcium, or manganese. In NG108-15 cell membranes, only sodium was effective in promoting inhibition of [125I]beta h-endorphin binding by GTP. The effect of GTP or Gpp(NH)p in the presence of sodium was also observed with guanosine diphosphate, but not guanosine monophosphate or any of the non-guanine nucleotides tested. These results indicate that the presence of monovalent cations is required for regulation of [125I]beta h-endorphin binding by guanine nucleotides, and that the specificity of this cation requirement differs between the mu and delta receptor-containing cell lines.
authors.affiliation: Department of Pharmacology, University of Rochester, School of Medicine and Dentistry, NY 14642.
authors.forename: D E
authors.initials: DE
authors.lastname: Selley
authors.forename: J M
authors.initials: JM
authors.lastname: Bidlack
mesh_terms: D002412:Cations; D002462:Cell Membrane / Q000378:metabolism; D020875:Enkephalin, Ala(2)-MePhe(4)-Gly(5)-; D020881:Enkephalin, D-Penicillamine (2,5)-; D004743:Enkephalin, Leucine / Q000031:analogs & derivatives*; D004745:Enkephalins / Q000378:metabolism; D005910:Glioma; D006150:Guanine Nucleotides / Q000494:pharmacology*; D006153:Guanosine Diphosphate / Q000494:pharmacology; D006160:Guanosine Triphosphate / Q000494:pharmacology; D006165:Guanylyl Imidodiphosphate / Q000494:pharmacology; D006801:Humans; D006822:Hybrid Cells; D009447:Neuroblastoma; D009842:Oligopeptides / Q000378:metabolism; D011957:Receptors, Opioid / Q000187:drug effects / Q000378:metabolism*; D017465:Receptors, Opioid, delta; D017450:Receptors, Opioid, mu; D012965:Sodium Chloride / Q000494:pharmacology; D014407:Tumor Cells, Cultured; D001615:beta-Endorphin / Q000378:metabolism*
chemical_list: D002412:Cations; D004745:Enkephalins; D006150:Guanine Nucleotides; D009842:Oligopeptides; D011957:Receptors, Opioid; D017465:Receptors, Opioid, delta; D017450:Receptors, Opioid, mu; D020875:Enkephalin, Ala(2)-MePhe(4)-Gly(5)-; D006153:Guanosine Diphosphate; D006165:Guanylyl Imidodiphosphate; D012965:Sodium Chloride; D004743:Enkephalin, Leucine; D001615:beta-Endorphin; C034318:enkephalin, Ser(2), Leu(5), Thr(6)-; D006160:Guanosine Triphosphate; D020881:Enkephalin, D-Penicillamine (2,5)-