Immunochemical mapping of human lutropin: I. Delineation of a conformational antigenic determinant.
Lutropin (LH), follitropin (FSH), thyrotropin (TSH) and choriogonadotropin (CG) are assembled of two non-covalently alpha (alpha) and beta (beta) subunits. We studied the discontinuous antigenic regions recognized by a monoclonal anti-hLH antibody designated as LH05 which binds to hLH, hCG and hTSH and does not cross-react with either the free subunits or hFSH. LH05 and an antibody designated HT13, recognizing an epitope partly comprizing the alpha64-76 region, did not bind simultaneously to hCG. Furthermore, LH05 was unable to combine with an anti-peptide antibody (LHP03) directed to residues 43-52 of hLHbeta. Thus, LH05 recognizes an epitope partly overlapping with those recognized by HT13 and LHP03. Using various hybrid molecules, we showed that the human alpha-subunit plays a critical role in the assembly of the epitope that, in contrast, contains amino acid residues conserved in the various beta-subunit of several species. Together, our results suggest that the amino acids Leu49-Pro50, Tyr59-Arg60 and Leu86-Ser87 in the hLHbeta and the alpha64-76 region are probably included in the epitope recognized by LH05 which appeared to be not accessible on the CG/LH receptor.
Robert
P
P
Service d'Immunologie Moléculaire, Institut Gustave-Roussy, Villejuif, France.
Troalen
F
F
Bellet
D
D
Bousfield
G R
GR
Bidart
J M
JM
D018604:Epitope Mapping; D000939:Epitopes / Q000276:immunology*; D006801:Humans; D007120:Immunochemistry; D007986:Luteinizing Hormone / Q000737:chemistry / Q000276:immunology*; D011487:Protein Conformation
D000939:Epitopes; D007986:Luteinizing Hormone