Open AccessA Defined Epitope on the Human Choriogonadotropin α‐Subunit Interacts with the Second Extracellular Loop of the Transmembrane Domain of the Lutropidchoriogonadotropin Receptor
Author(s) -
Couture Laurence,
Remy JeanJacques,
Rabesona Hanitra,
Troalen Frédéric,
PajotAugy Edith,
Bozon Véronique,
Haertle Thomas,
Bidart JeanMichel,
Salesse Roland
Publication year - 1996
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1996.00627.x
Subject(s) - epitope , extracellular , receptor , g alpha subunit , protein subunit , biology , peptide , transmembrane protein , transmembrane domain , microbiology and biotechnology , interleukin 10 receptor, alpha subunit , monoclonal antibody , enzyme linked receptor , biochemistry , antibody , gene , genetics
The monoclonal antibody, HT13 recognizes human choriogonadotropin (CG) bound to the extracellular domain of its receptor, but not to the fullolength receptor. The HT13 epitope is located in the regions of residues 15–17 and 73–75 of the human CG α‐subunit. Only one synthetic peptide, lutropin (LH)/CG‐receptor‐(481–497)‐peptide (EL2 peptide), which spans the second putative extracellular loop of the LWCG‐receptor endodomain, prevents recognition of human CG by HT13 mAb. EL2 peptide decreases hormone‐induced cAMP production, but not high‐affinity binding. An anti‐EL2 serum also displays the capacity to inhibit human CG‐stimulated cAMP production. These results suggest that the second extracellular loop of the receptor is in contact with the HT13 epitope of human CG a‐subunit and is involved in signal transduction. A relative orientation of the hormone versus the endodomain is proposed.