Specific binding of 2-[125I]melatonin by partially purified membranes of rat thymus

M. A. Lopez-Gonzalez, A. Martin-Cacao, J. R. Calvo, R. J. Reiter, C. Osuna, J. M. Guerrero

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Abstract

Melatonin binding sites were characterized in partially rat thymus membranes. The specific binding of 2-[125I]iodomelatonin ([125I]MEL) to thymus membranes was dependent on time and temperature, stable, saturable, and reversible. Concentration-dependent binding of [125I]MEL to thymus membranes was saturable and resulted in a linear Scatchard plot, suggesting binding to a single class binding to sites. The Kd for this single site was 0.47 nM with a binding capacity of 1.01 pM. In competition studies, the specific binding of [125I]MEL to thymus membranes was inhibited by increasing concentrations of native melatonin. Scatchard analysis showed that, unlike in a saturation studies with [125I]MEL, data were compatible with the existence of two classes of binding sites: a high-affinity site with a Kd of 1.72 ± 0.25 nM and a binding capacity of 1.40 ± 0.18 pM, and a low-affinity site with a Kd of 1226 ± 325 Nm and a binding capacity of 460 ± 87 nM. Interestingly, Kd and BC values of the high-affinity binding site described by competition studies are similar to those obtained by saturation studies with [su125I]MEL. Binding of [125I]MEL to thymus membranes was specific as indicated by the fact no other precursor or derivative was as potent as melatonin in inhibiting the binding of [125I]MEL to membranes. Results strongly that melatonin is involved in regulation of thymus activity.

Original languageEnglish (US)
Pages (from-to)121-126
Number of pages6
JournalJournal of Neuroimmunology
Volume45
Issue number1-2
DOIs
Publication statusPublished - Jun 1993

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Keywords

  • Immune system
  • Melatoni binding sites
  • Melatonin
  • Pineal
  • Thymus

ASJC Scopus subject areas

  • Immunology and Allergy
  • Immunology
  • Neurology
  • Clinical Neurology

Cite this

Lopez-Gonzalez, M. A., Martin-Cacao, A., Calvo, J. R., Reiter, R. J., Osuna, C., & Guerrero, J. M. (1993). Specific binding of 2-[125I]melatonin by partially purified membranes of rat thymus. Journal of Neuroimmunology, 45(1-2), 121-126. https://doi.org/10.1016/0165-5728(93)90171-T