TRIFUNCTIONAL LIGANDS: A RADIOIODINATED HIGH AFFINITY ACYLATING ANTAGONIST FOR THE A1 ADENOSINE RECEPTOR

Kenneth A Jacobson; Mark E Olah; Gary L Stiles

TRIFUNCTIONAL LIGANDS: A RADIOIODINATED HIGH AFFINITY ACYLATING ANTAGONIST FOR THE A₁ ADENOSINE RECEPTOR

Pharmacol Commun. 1992;1(2):145-154.

Authors

Kenneth A Jacobson¹, Mark E Olah¹, Gary L Stiles¹

Affiliation

¹ Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892.

PMID: 25374448
PMCID: PMC4217529

Abstract

A new xanthine (adenosine antagonist) radioligand that binds covalently to A_1-adenosine receptors was prepared and used as a receptor probe. BH-DITC-XAC was synthesized via a trifunctional aryl diisothiocyanate crosslinker. containing the p-hydroxyphenylpropionyl group for radioiodination. The xanthine competed against agonist or antagonist A₁ receptor radioligands in bovine brain membranes with an IC₅₀, of 40nM. ¹²⁵I-BH-DITC-XAC, prepared directly by the chloramine T method and purified by HPLC. bound specifically to A₁ receptors. This binding was inhibited in the presence of the adenosine agonists R-PIA, S-PIA. and NECA in a dose dependent manner and with the order of potency characteristic of bovine A₁ receptors. Incubation of affinity purified bovine A₁-receptors with ¹²⁵I-BH-DITC-XAC (0.8 nM) for 2 hours resulted in the specific and clean labelling of a polypeptide band corresponding to MW 36,000, identical to that previously found for the A₁ receptor.

Keywords: adenosine receptors; affinity labeling; radioiodination; xanthines.

Abstract

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