The goal of these studies was to devise a model that explains how human chorionic gonadotropin (hCG) interacts with lutropin (LH) receptors to elicit a hormone signal. Here we show that -subunit residues near the N terminus, the exposed surface of the cysteine knot, and portions of the first and third loops most distant from the -subunit interface were recognized by antibodies that bound to hCG-receptor complexes. These observations were combined with similar data obtained for the -subunit (Cosowsky, L., Rao, S. N. V., Macdonald, G. J., Papkoff, H., Campbell, R. K., and Moyle, W. R.(1995) J. Biol. Chem. 270, 20011-20019), information on residues of hCG that can be changed without disrupting hormone function, the crystal structure of deglycosylated hCG, and the crystal structure of a leucine-repeat protein to devise a model of hCG-receptor interaction. This model suggests that the extracellular domain of the LH receptor is ``U-'' or ``J''-shaped and makes several contacts with the transmembrane domain. High affinity hormone binding results from interactions between residues in the curved portion of the extracellular domain of the receptor and the groove in the hormone formed by the apposition of the second -subunit loop and the first and third -subunit loops. Most of the remainder of the hormone is found in the large space between the arms of the extracellular domain and makes few, if any, additional specific contacts with the receptor needed for high affinity binding. Signal transduction is caused by steric or other influences of the hormone on the distance between the arms of the extracellular domain, an effect augmented by the oligosaccharides. Because the extracellular domain is coupled at multiple sites to the transmembrane domain, the change in conformation of the extracellular domain is relayed to the transmembrane domain and subsequently to the cytoplasmic surface of the plasma membrane. While the model does not require the hormone to contact the transmembrane domain to initiate signal transduction, small portions of both subunits may be near the transmembrane domain and assist in initiating the hormonal signal. This is the first model that is consistent with all known information on the activity of the gonadotropins including the amounts of the hormone that are exposed in the hormone-receptor complex, the apparent lack of specific contacts between much of the hormone and the receptor, and the roles of the oligosaccharides in signal transduction. This model differs from existing models of hormone action in that the extracellular domain has a much larger role in hormone action than serving as a high affinity hormone trap.

CiteULike

Complore

Connotea

Del.icio.us

Digg

Reddit

Technorati

This article has been cited by other articles:

				S.F. de Medeiros and R.J. Norman Human choriogonadotrophin protein core and sugar branches heterogeneity: basic and clinical insights Hum. Reprod. Update, January 1, 2009; 15(1): 69 - 95. [Abstract] [Full Text] [PDF]

				S. Roy, S. Setlur, R. A. Gadkari, H. N. Krishnamurthy, and R. R. Dighe Translational Fusion of Two {beta}-Subunits of Human Chorionic Gonadotropin Results in Production of a Novel Antagonist of the Hormone Endocrinology, August 1, 2007; 148(8): 3977 - 3986. [Abstract] [Full Text] [PDF]

				M. Y.-K. Leung, P. J. Steinbach, D. Bear, V. Baxendale, P. Y. Fechner, O. M. Rennert, and W.-Y. Chan Biological Effect of a Novel Mutation in the Third Leucine-Rich Repeat of Human Luteinizing Hormone Receptor Mol. Endocrinol., October 1, 2006; 20(10): 2493 - 2503. [Abstract] [Full Text] [PDF]

				R A Gadkari, S Roy, N Rekha, N Srinivasan, and R R Dighe Identification of a heterodimer-specific epitope present in human chorionic gonadotrophin (hCG) using a monoclonal antibody that can distinguish between hCG and human LH J. Mol. Endocrinol., June 1, 2005; 34(3): 879 - 887. [Abstract] [Full Text] [PDF]

				G. Kleinau, H. Jaschke, S. Neumann, J. Lattig, R. Paschke, and G. Krause Identification of a Novel Epitope in the Thyroid-stimulating Hormone Receptor Ectodomain Acting as Intramolecular Signaling Interface J. Biol. Chem., December 3, 2004; 279(49): 51590 - 51600. [Abstract] [Full Text] [PDF]

				Y. Xing, W. Lin, M. Jiang, D. Cao, R. V. Myers, M. P. Bernard, and W. R. Moyle Use of Protein Knobs to Characterize the Position of Conserved {alpha}-Subunit Regions in Lutropin Receptor Complexes J. Biol. Chem., October 22, 2004; 279(43): 44427 - 44437. [Abstract] [Full Text] [PDF]

				M. P. Bernard, W. Lin, D. Cao, R. V. Myers, Y. Xing, and W. R. Moyle Only a Portion of the Small Seatbelt Loop in Human Choriogonadotropin Appears Capable of Contacting the Lutropin Receptor J. Biol. Chem., October 22, 2004; 279(43): 44438 - 44441. [Abstract] [Full Text] [PDF]

				W. R. Moyle, Y. Xing, W. Lin, D. Cao, R. V. Myers, J. E. Kerrigan, and M. P. Bernard Model of Glycoprotein Hormone Receptor Ligand Binding and Signaling J. Biol. Chem., October 22, 2004; 279(43): 44442 - 44459. [Abstract] [Full Text] [PDF]

				Y. Xing, R. V. Myers, D. Cao, W. Lin, M. Jiang, M. P. Bernard, and W. R. Moyle Glycoprotein Hormone Assembly in the Endoplasmic Reticulum: II. MULTIPLE ROLES OF A REDOX SENSITIVE {beta}-SUBUNIT DISULFIDE SWITCH J. Biol. Chem., August 20, 2004; 279(34): 35437 - 35448. [Abstract] [Full Text] [PDF]

				G. B. Fralish, B. Dattilo, and D. Puett Structural Analysis of Yoked Chorionic Gonadotropin-Luteinizing Hormone Receptor Ectodomain Complexes by Circular Dichroic Spectroscopy Mol. Endocrinol., July 1, 2003; 17(7): 1192 - 1202. [Abstract] [Full Text] [PDF]

				P. Narayan, J. Gray, and D. Puett Yoked Complexes of Human Choriogonadotropin and the Lutropin Receptor: Evidence that Monomeric Individual Subunits Are Inactive Mol. Endocrinol., December 1, 2002; 16(12): 2733 - 2745. [Abstract] [Full Text] [PDF]

				K. Angelova, F. Fanelli, and D. Puett A Model for Constitutive Lutropin Receptor Activation Based on Molecular Simulation and Engineered Mutations in Transmembrane Helices 6 and 7 J. Biol. Chem., August 23, 2002; 277(35): 32202 - 32213. [Abstract] [Full Text] [PDF]

				M. Ascoli, F. Fanelli, and D. L. Segaloff The Lutropin/Choriogonadotropin Receptor, A 2002 Perspective Endocr. Rev., April 1, 2002; 23(2): 141 - 174. [Abstract] [Full Text] [PDF]

				M. W. Szkudlinski, V. Fremont, C. Ronin, and B. D. Weintraub Thyroid-Stimulating Hormone and Thyroid-Stimulating Hormone Receptor Structure-Function Relationships Physiol Rev, April 1, 2002; 82(2): 473 - 502. [Abstract] [Full Text] [PDF]

				Y. Xing, W. Lin, M. Jiang, R. V. Myers, D. Cao, M. P. Bernard, and W. R. Moyle Alternatively Folded Choriogonadotropin Analogs. IMPLICATIONS FOR HORMONE FOLDING AND BIOLOGICAL ACTIVITY J. Biol. Chem., December 7, 2001; 276(50): 46953 - 46960. [Abstract] [Full Text] [PDF]

				M. Einstein, W. Lin, G. J. Macdonald, and W. R. Moyle Partial Restoration Of Lutropin Activity by an Intersubunit Disulfide Bond: Implications For Structure/Function Studies Experimental Biology and Medicine, June 1, 2001; 226(6): 581 - 590. [Abstract] [Full Text] [PDF]

				G. B. Fralish, P. Narayan, and D. Puett High-Level Expression of a Functional Single-Chain Human Chorionic Gonadotropin-Luteinizing Hormone Receptor Ectodomain Complex in Insect Cells Endocrinology, April 1, 2001; 142(4): 1517 - 1524. [Abstract] [Full Text]

				M. C. Gershengorn and R. Osman Minireview: Insights into G Protein-Coupled Receptor Function Using Molecular Models Endocrinology, January 1, 2001; 142(1): 2 - 10. [Abstract] [Full Text] [PDF]

				A. P. N. Themmen and I. T. Huhtaniemi Mutations of Gonadotropins and Gonadotropin Receptors: Elucidating the Physiology and Pathophysiology of Pituitary-Gonadal Function Endocr. Rev., October 1, 2000; 21(5): 551 - 583. [Abstract] [Full Text]

				M. Kanda, A. Jablonka-Shariff, A. Sato, M. R. Pixley, E. Bos, T. Hiro’oka, D. Ben-Menahem, and I. Boime Genetic Fusion of an {alpha}-Subunit Gene to the Follicle-Stimulating Hormone and Chorionic Gonadotropin-{beta} Subunit Genes: Production of a Bifunctional Protein Mol. Endocrinol., November 1, 1999; 13(11): 1873 - 1881. [Abstract] [Full Text]

				N. Bhowmick, P. Narayan, and D. Puett Identification of Ionizable Amino Acid Residues on the Extracellular Domain of the Lutropin Receptor Involved in Ligand Binding Endocrinology, October 1, 1999; 140(10): 4558 - 4563. [Abstract] [Full Text]

				K. Nakamura, X. Liu, and M. Ascoli The Rate of Internalization of the Gonadotropin Receptors Is Greatly Affected by the Origin of the Extracellular Domain J. Biol. Chem., September 3, 1999; 274(36): 25426 - 25432. [Abstract] [Full Text] [PDF]

				C. A. Alvarez, P. Narayan, J. Huang, and D. Puett Characterization of a Region of the Lutropin Receptor Extracellular Domain Near Transmembrane Helix 1 That Is Important in Ligand-Mediated Signaling Endocrinology, April 1, 1999; 140(4): 1775 - 1782. [Abstract] [Full Text]

				S. Y. Hsu, S.-G. Liang, and A. J. W. Hsueh Characterization of Two LGR Genes Homologous to Gonadotropin and Thyrotropin Receptors with Extracellular Leucine-Rich Repeats and a G Protein-Coupled, Seven-Transmembrane Region Mol. Endocrinol., December 1, 1998; 12(12): 1830 - 1845. [Abstract] [Full Text]

				S.-M. Wu, K. M. Hallermeier, L. Laue, C. Brain, A. C. Berry, D. B. Grant, J. E. Griffin, J. D. Wilson, G. B. Cutler Jr., and W.-Y. Chan Inactivation of the Luteinizing Hormone/Chorionic Gonadotropin Receptor by an Insertional Mutation in Leydig Cell Hypoplasia Mol. Endocrinol., November 1, 1998; 12(11): 1651 - 1660. [Abstract] [Full Text]

				E. C. Yurewicz, A. G. Sacco, S. K. Gupta, N. Xu, and D. A. Gage Hetero-oligomerization-dependent Binding of Pig Oocyte Zona Pellucida Glycoproteins ZPB and ZPC to Boar Sperm Membrane Vesicles J. Biol. Chem., March 27, 1998; 273(13): 7488 - 7494. [Abstract] [Full Text] [PDF]

				M. Simoni, J. Gromoll, and E. Nieschlag The Follicle-Stimulating Hormone Receptor: Biochemistry, Molecular Biology, Physiology, and Pathophysiology Endocr. Rev., December 1, 1997; 18(6): 739 - 773. [Abstract] [Full Text]

				Y. Osuga, M. Hayashi, M. Kudo, M. Conti, B. Kobilka, and A. J. W. Hsueh Co-expression of Defective Luteinizing Hormone Receptor Fragments Partially Reconstitutes Ligand-induced Signal Generation J. Biol. Chem., October 3, 1997; 272(40): 25006 - 25012. [Abstract] [Full Text] [PDF]

				M. Grossmann, B. D. Weintraub, and M. W. Szkudlinski Novel Insights into the Molecular Mechanisms of Human Thyrotropin Action: Structural, Physiological, and Therapeutic Implications for the Glycoprotein Hormone Family Endocr. Rev., August 1, 1997; 18(4): 476 - 501. [Abstract] [Full Text] [PDF]

				A. Sato, E. Perlas, D. Ben-Menahem, M. Kudo, M. R. Pixley, M. Furuhashi, A. J. W. Hsueh, and I. Boime Cystine Knot of the Gonadotropin alpha  Subunit Is Critical for Intracellular Behavior but Not for in Vitro Biological Activity J. Biol. Chem., July 18, 1997; 272(29): 18098 - 18103. [Abstract] [Full Text] [PDF]

				M. Grossmann, M. W. Szkudlinski, R. Wong, J. A. Dias, T. H. Ji, and B. D. Weintraub Substitution of the Seat-belt Region of the Thyroid-stimulating Hormone (TSH) beta -Subunit with the Corresponding Regions of Choriogonadotropin or Follitropin Confers Luteotropic but Not Follitropic Activity to Chimeric TSH J. Biol. Chem., June 13, 1997; 272(24): 15532 - 15540. [Abstract] [Full Text] [PDF]

				D. Ben-Menahem, M. Kudo, M. R. Pixley, A. Sato, N. Suganuma, E. Perlas, A. J.W. Hsueh, and I. Boime The Biologic Action of Single-chain Choriogonadotropin Is Not Dependent on the Individual Disulfide Bonds of the beta Subunit J. Biol. Chem., March 14, 1997; 272(11): 6827 - 6830. [Abstract] [Full Text] [PDF]

				L. Cosowsky, W. Lin, Y. Han, M. P. Bernard, RobertK. Campbell, and WilliamR. Moyle Influence of Subunit Interactions on Lutropin Specificity. IMPLICATIONS FOR STUDIES OF GLYCOPROTEIN HORMONE FUNCTION J. Biol. Chem., February 7, 1997; 272(6): 3309 - 3314. [Abstract] [Full Text] [PDF]

				C. Wu, P. Narayan, and D. Puett Protein Engineering of a Novel Constitutively Active Hormone-Receptor Complex J. Biol. Chem., December 6, 1996; 271(49): 31638 - 31642. [Abstract] [Full Text] [PDF]

				L. Cosowsky, S. N. V. Rao, G. J. Macdonald, H. Papkoff, R. K. Campbell, and W. R. Moyle The Groove between the alpha- and beta-Subunits of Hormones with Lutropin (LH) Activity Appears to Contact the LH Receptor, and Its Conformation Is Changed during Hormone Binding J. Biol. Chem., August 25, 1995; 270(34): 20011 - 20019. [Abstract] [Full Text] [PDF]

				Y. S. Song, I. Ji, J. Beauchamp, N. W. Isaacs, and T. H. Ji Hormone Interactions to Leu-rich Repeats in the Gonadotropin Receptors. I. ANALYSIS OF LEU-RICH REPEATS OF HUMAN LUTEINIZING HORMONE/CHORIONIC GONADOTROPIN RECEPTOR AND FOLLICLE-STIMULATING HORMONE RECEPTOR J. Biol. Chem., January 26, 2001; 276(5): 3426 - 3435. [Abstract] [Full Text] [PDF]

				Y. S. Song, I. Ji, J. Beauchamp, N. W. Isaacs, and T. H. Ji Hormone Interactions to Leu-rich Repeats in the Gonadotropin Receptors. II. ANALYSIS OF LEU-RICH REPEAT 4 OF HUMAN LUTEINIZING HORMONE/CHORIONIC GONADOTROPIN RECEPTOR J. Biol. Chem., January 26, 2001; 276(5): 3436 - 3442. [Abstract] [Full Text] [PDF]

				M. Jeoung, T. Phang, Y. S. Song, I. Ji, and T. H. Ji Hormone Interactions to Leu-rich Repeats in the Gonadotropin Receptors. III. PHOTOAFFINITY LABELING OF HUMAN CHORIONIC GONADOTROPIN WITH RECEPTOR LEU-RICH REPEAT 4 PEPTIDE J. Biol. Chem., January 26, 2001; 276(5): 3443 - 3450. [Abstract] [Full Text] [PDF]

				K. Nakabayashi, M. Kudo, B. Kobilka, and A. J. W. Hsueh Activation of the Luteinizing Hormone Receptor Following Substitution of Ser-277 with Selective Hydrophobic Residues in the Ectodomain Hinge Region J. Biol. Chem., September 22, 2000; 275(39): 30264 - 30271. [Abstract] [Full Text] [PDF]

				H. Zeng, T. Phang, Y. S. Song, I. Ji, and T. H. Ji The Role of the Hinge Region of the Luteinizing Hormone Receptor in Hormone Interaction and Signal Generation J. Biol. Chem., January 26, 2001; 276(5): 3451 - 3458. [Abstract] [Full Text] [PDF]

				A. Schmidt, R. MacColl, B. Lindau-Shepard, D. R. Buckler, and J. A. Dias Hormone-induced Conformational Change of the Purified Soluble Hormone Binding Domain of Follitropin Receptor Complexed with Single Chain Follitropin J. Biol. Chem., June 22, 2001; 276(26): 23373 - 23381. [Abstract] [Full Text] [PDF]

				S. D. Mahale, J. Cavanagh, A. Schmidt, R. MacColl, and J. A. Dias Autologous Biological Response Modification of the Gonadotropin Receptor J. Biol. Chem., April 6, 2001; 276(15): 12410 - 12419. [Abstract] [Full Text] [PDF]