Synthetic beta-endorphin-like peptide immunorphin binds to non-opioid receptors for beta-endorphin on T lymphocytes.
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]beta-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]beta-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.
Navolotskaya
E V
EV
Branch of Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry of the Russian Academy of Sciences, 142290, Pushchino, Moscow Region, Russia. navolots@fibkh.serpukhov.su
Malkova
N V
NV
Zargarova
T A
TA
Lepikhova
T N
TN
Zav'yalov
V P
VP
Lipkin
V M
VM
D000595:Amino Acid Sequence; D006801:Humans; D007127:Immunoglobulin Constant Regions; D007142:Immunoglobulin gamma-Chains; D009842:Oligopeptides / Q000737:chemistry / Q000378:metabolism*; D010446:Peptide Fragments / Q000737:chemistry / Q000378:metabolism*; D011957:Receptors, Opioid / Q000378:metabolism*; D013601:T-Lymphocytes / Q000378:metabolism*; D001615:beta-Endorphin
D007127:Immunoglobulin Constant Regions; D007142:Immunoglobulin gamma-Chains; D009842:Oligopeptides; D010446:Peptide Fragments; D011957:Receptors, Opioid; C445661:immunorphin; D001615:beta-Endorphin