Melatonin binding proteins identified in the rat brain by affinity labeling

Moshe Laudon, Nava Zisapel*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


N-Bromoacetyl-2-iodo-5-methoxytryptamine (BIM), a novel derivative of the biologically active melatonin analog, 2-iodomelatonin, was prepared and used to identify melatonin binding proteins in rat brain synaptosomes. Incubation of the synaptosomes with BIM resulted in a time and concentration dependent, irreversible inhibition of 2-[125I]iodomelatonin binding. In parallel, the radioactive form of BIM, N-bromoacetyl-2-[125I]iodo-5-methoxytryptamine [125I]BIM) became incorporated into the synaptosomes. The incorporation of [125I]BIM was inhibited by BIM, 2-iodomelatonin and melatonin but not by 5-methoxytryptamine or N-acetyl serotonin. [125I]BIM became covalently attached to three polypeptides with apparent molecular weight values of 92, 55 and 45 kDa; the labeling of all three proteins was markedly inhibited by melatonin. These results indicate that the 92, 55 and 45 kDa polypeptides are melatonin binding proteins.

Original languageEnglish
Pages (from-to)105-108
Number of pages4
JournalFEBS Letters
Issue number1-2
StatePublished - 19 Aug 1991


  • Affinity labeling
  • Brain
  • Iodomelatonin
  • Melatonin


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