title: Detection of nonopioid β-endorphin receptor in the rat myocardium.
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 [(3)H]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 [(3)H]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, [Met(5)]enkephalin and [Leu(5)]enkephalin. Thus, β-endorphin, immunorphin and octarphin bind to the common high-affinity naloxone-insensitive receptor of the rat myocardial membranes.
authors: Branch of Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry of the Russian Academy of Sciences, Science Avenue, 6, Pushchino, Moscow Region 142290, Russia.
authors: Yulia N
authors: YN
authors: Nekrasova
authors: Yury A
authors: YA
authors: Zolotarev
authors: Elena V
authors: EV
authors: Navolotskaya
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001667:Binding, Competitive; D007127:Immunoglobulin Constant Regions / Q000737:chemistry*; D007142:Immunoglobulin gamma-Chains / Q000737:chemistry*; D008297:Male; D009206:Myocardium / Q000737:chemistry*; D009270:Naloxone / Q000737:chemistry; D009292:Narcotic Antagonists / Q000737:chemistry; D009842:Oligopeptides / Q000737:chemistry*; D010446:Peptide Fragments / Q000737:chemistry*; D011485:Protein Binding; D051381:Rats; D017208:Rats, Wistar; D011957:Receptors, Opioid / Q000737:chemistry*; D001615:beta-Endorphin / Q000737:chemistry*
chemical_list: D007127:Immunoglobulin Constant Regions; D007142:Immunoglobulin gamma-Chains; D009292:Narcotic Antagonists; D009842:Oligopeptides; D010446:Peptide Fragments; D011957:Receptors, Opioid; C445661:immunorphin; C555005:octarphin; D009270:Naloxone; D001615:beta-Endorphin