Peptide mapping of intersubunit and receptor interactions of human choriogonadotropin.
Seven peptides covering the entire sequence of human choriogonadotropin (hCG) alpha-subunit, eight peptides covering the hCG beta-subunit sequence and two peptides, one of human beta-lutropin and one of beta-thyrotropin were synthesized. We checked their ability to prevent reassociation between hCG alpha- and beta-subunits and between hCG and its receptor. Only the alpha 1-22, alpha 59-92 and beta 1-16 peptides inhibited the reassociation between the alpha- and beta-subunits of hCG with an ED50 of respectively 2 mM, 2 mM and 4 mM. Using porcine Leydig cells in primary culture, we showed that alpha 33-59, alpha 41-59 and beta 1-16 peptides decreased both the specific binding to the cell surface and the internalization of [125I]hCG and [125I]porcine LH with ED50 of 0.3, 0.1 and 0.5 mM, respectively. From these results, the following minimal area may be assigned, (i) to the alpha-beta interaction: alpha 5-16, alpha 52-72 (or alpha 59-70) and beta 8-16, and (ii) to the hormone-receptor association: alpha 41-45 and beta 8-16.
Salesse
R
R
Unité d'Ingénierie des Protéines, Biotechnologie, INRA, Jouy-en-Josas, France.
Bidart
J M
JM
Troalen
F
F
Bellet
D
D
Garnier
J
J
D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002478:Cells, Cultured; D006063:Chorionic Gonadotropin / Q000378:metabolism; D006801:Humans; D007985:Leydig Cells / Q000378:metabolism; D007986:Luteinizing Hormone / Q000378:metabolism; D008297:Male; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000378:metabolism; D010449:Peptide Mapping; D011974:Receptors, LH / Q000378:metabolism
D006063:Chorionic Gonadotropin; D010446:Peptide Fragments; D011974:Receptors, LH; D007986:Luteinizing Hormone