Effects of transition metals on TRH-receptor interaction.
The interaction of TRH receptors and metal ions was investigated. Although the addition of a physiological serum concentration (20 microM) of Zn2+ or Cu2+ to the TRH radioreceptor assay reaction mixture significantly increased the binding capacity, pretreatment of crude synaptic membranes with Ni2+, Zn2+, Cu2+ or Pd2+ resulted in a significant loss of binding activity. The receptor preparation was bound to [3H]TRH in the presence of 10 mM Ni2+ and was solubilized by Triton X-100. Gel filtration was carried out with cold Tris-HCl-Triton buffer without Ni2+. The molecular weight of the solubilized TRH-macromolecular complex was about 300,000 daltons, and Ni2+ was found in the same fraction as the solubilized TRH-receptor. These results suggest that metal ions have inverse effects in different steps of TRH-receptor interaction and that a TRH-receptor molecule indicates a Ni-binding molecule.
D000818:Animals; D003300:Copper / Q000494:pharmacology; D008670:Metals / Q000494:pharmacology*; D009532:Nickel / Q000494:pharmacology; D010165:Palladium / Q000494:pharmacology; D011869:Radioligand Assay; D051381:Rats; D011956:Receptors, Cell Surface / Q000187:drug effects* / Q000378:metabolism; D018025:Receptors, Thyrotropin-Releasing Hormone; D013570:Synaptic Membranes / Q000378:metabolism*; D013973:Thyrotropin-Releasing Hormone / Q000378:metabolism*; D015032:Zinc / Q000494:pharmacology
D008670:Metals; D011956:Receptors, Cell Surface; D018025:Receptors, Thyrotropin-Releasing Hormone; D010165:Palladium; D013973:Thyrotropin-Releasing Hormone; D003300:Copper; D009532:Nickel; D015032:Zinc