Receptor-binding properties of the peptides corresponding to the beta-endorphin-like sequence of human immunoglobulin G.
The decapeptide H2N-Ser-Leu-Thr-Cys-Leu-Val-Lys-Gly-Phe-Tyr-COOH (termed immunorphin) corresponding to the sequence 364-373 of the CH3 domain of the human immunoglobulin G1 Eu heavy chain and displaying a 43% identity with the antigenic determinant of beta-endorphin was synthesized. Immunorphin was found to compete with 125I-beta-endorphin for high-affinity receptors on murine peritoneal macrophages (K = 2.5 +/- 0.9 x 10(-9) M) and with 3H-morphin for receptors on murine thymocytes (Ki = 2.7 +/- 0.6 x 10(-9) M) and murine macrophages (Ki = 5.9 +/- 0.7 x 10(-9) M). In particular two types of receptors to 125I-beta-endorphin with Kd1 = 6.1 +/- 0.6 x 10(-9) M and Kd2 = 3.1 +/- 0.2 x 10(-8) M were revealed on macrophages. The second type of receptors interacted with 125I-beta-endorphin, 3H-Met-enkephalin, 3H-Leu-enkephalin and 3H-morphin; the first displayed reactivity with 125I-beta-endorphin, 3H-morphin and immunorphin. The first type receptors are not present on murine brain cells nor are inhibited by naloxone. A minimum fragment of immunorphin practically completely retaining its inhibitory activity in the competition tests with 125I-beta-endorphin for common receptors on thymocytes was found to correspond to the tetrapeptide H2N-Lys-Gly-Phe-Tyr-COOH (Ki = 5.6 +/- 0.5 x 10(-9) M).
Zav'yalov
V P
VP
Institute of Engineering Immunology, Chekhov District, Moscow Region, Russia.
Zaitseva
O R
OR
Navolotskaya
E V
EV
Abramov
V M
VM
Volodina EYu
Mitin
Y V
YV
D006801:Humans; D007074:Immunoglobulin G / Q000737:chemistry* / Q000378:metabolism*; D010455:Peptides / Q000737:chemistry* / Q000378:metabolism*; D011485:Protein Binding / Q000276:immunology; D011971:Receptors, Immunologic / Q000737:chemistry* / Q000378:metabolism*; D001615:beta-Endorphin / Q000737:chemistry* / Q000378:metabolism*
D007074:Immunoglobulin G; D010455:Peptides; D011971:Receptors, Immunologic; D001615:beta-Endorphin