Detection of nonopioid β‐endorphin receptor in the rat myocardium |
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Authors: | Yulia N. Nekrasova Yury A. Zolotarev Elena V. Navolotskaya |
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Affiliation: | 1. Branch of Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry of the Russian Academy of Sciences, , Pushchino, Moscow Region, 142290 Russia;2. Institute of Molecular Genetics of the Russian Academy of Sciences, , Moscow, 123182 Russia |
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Abstract: | Two selective agonists of nonopioid β‐endorphin receptor, synthetic peptides TPLVTLFK (octarphin) and SLTCLVKGFY (immunorphin), were labeled with tritium to specific activity of 29 and 25 Ci/mmol, respectively. Both labeled peptides were found to bind to high‐affinity naloxone‐insensitive binding sites on the membranes isolated from the rat myocardium (Kd = 2.0 ± 0.2 and 2.5 ± 0.3 nM, respectively). The [3H]octarphin specific binding to the myocardial membranes was inhibited by unlabeled β‐endorphin (Ki = 1.9 ± 0.2 nM) and immunorphin (Ki = 2.2 ± 0.3 nM). The [3H]immunorphin specific binding with the membranes was inhibited by unlabeled β‐endorphin (Ki = 2.3 ± 0.3 nM) and octarphin (Ki = 2.4 ± 0.3 nM). The binding specificity study revealed that these binding sites were insensitive not only to naloxone but also to α‐endorphin, γ‐endorphin, [Met5]enkephalin and [Leu5]enkephalin. Thus, β‐endorphin, immunorphin and octarphin bind to the common high‐affinity naloxone‐insensitive receptor of the rat myocardial membranes. Copyright © 2011 European Peptide Society and John Wiley & Sons, Ltd. |
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Keywords: | β ‐endorphin peptides receptors myocardium |
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