Synthetic β-endorphin-like peptide immunorphin binds to non-opioid receptors for β-endorphin on T lymphocytes

• Published in: Peptides (New York, N.Y. : 1980) Vol. 22; no. 12; pp. 2009 - 2013
• Main Authors: Navolotskaya, Elena V, Malkova, Natalia V, Zargarova, Tatyana A, Lepikhova, Tatyana N, Zav’yalov, Vladimir P, Lipkin, Valery M
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.12.2001
• Subjects: Amino Acid Sequence; beta-Endorphin; Humans; Immunoglobulin Constant Regions; Immunoglobulin gamma-Chains; Oligopeptides - chemistry; Oligopeptides - metabolism; Peptide; Peptide Fragments - chemistry; Peptide Fragments - metabolism; Receptor; Receptors, Opioid - metabolism; T lymphocytes; T-Lymphocytes - metabolism; β-Endorphin; T lymphocytes; β-Endorphin; Receptor; Peptide
• ISSN: 0196-9781; 1873-5169
• DOI: 10.1016/S0196-9781(01)00563-0

The synthetic decapeptide H-SLTCLVKGFY-OH (termed immunorphin) corresponding to the sequence 364–373 of the CH3 domain of human immunoglobulin G heavy chain was found to compete with [ 125I]β-endorphin for high-affinity receptors on T lymphocytes from the blood of healthy donors ( K i = 0.6 nM). Besides immunorphin, its synthetic fragments H-Val-Lys-Gly-Phe-Tyr-OH ( K i = 15 nM), H-Leu-Val-Lys-Gly-Phe-Tyr-OH ( K i = 8.0 nM), H-Cys-Leu-Val-Lys-Gly-Phe-Tyr-OH ( K i = 3.4 nM), H-Thr-Cys-Leu-Val-Lys-Gly-Phe-Tyr-OH ( K i = 2.2 nM), H-Leu-Thr-Cys-Leu-Val-Lys-Gly-Phe-Tyr-OH ( K i = 1.0 nM) possessed the ability to inhibit specific binding of [ 125I]β-endorphin to T lymphocytes. Tests of the specificity of the receptors revealed that they are not sensitive to naloxone and Met-enkephalin, i.e. they are not opioid receptors. K d values characterizing the specific binding of 125I- labeled immunorphin and its fragment H-Val-Lys-Gly-Phe-Tyr-OH to the receptors have been determined to be 7.4 nM and 36.3 nM, respectively.