This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Copyright Permission Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Mizutori, Y. Articles by Rapoport, B. Search for Related Content PubMed PubMed Citation Articles by Mizutori, Y. Articles by Rapoport, B. Pubmed/NCBI databases Compound via MeSH Substance via MeSH

The Thyrotropin Receptor Hinge Region Is Not Simply a Scaffold for the Leucine-Rich Domain but Contributes to Ligand Binding and Signal Transduction

Autoimmune Disease Unit, Cedars-Sinai Research Institute and University of California, Los Angeles, School of Medicine, Los Angeles, California 90048

Address all correspondence and requests for reprints to: Basil Rapoport, Cedars-Sinai Medical Center, 8700 Beverly Boulevard, Suite B-131, Los Angeles, California 90048. E-mail: rapoportb{at}cshs.org.

The glycoprotein hormone receptor hinge region connects the leucine-rich and transmembrane domains. The prevalent concept is that the hinge does not play a significant role in ligand binding and signal transduction. Portions of the hinge are redundant and can be deleted by mutagenesis or are absent in certain species. A minimal hinge will be more amenable to future investigation of its structure and function. We, therefore, combined and progressively extended previous deletions () in the TSH receptor (TSHR) hinge region (residues 277–418). TSHR287–366, 287–371, 287–376, and 287–384 progressively lost their response to TSH stimulation of cAMP generation in intact cells, consistent with a progressive loss of TSH binding. The longest deletion (TSHR287–384), reducing the hinge region from 141 to 43 amino acids, totally lost both functions. Surprisingly, however, with deletions extending from residues 371–384, constitutive (ligand-independent) activity increased severalfold, reversing the suppressive (inverse agonist) effect of the TSHR extracellular domain. TSHR-activating point mutations I486F and I568T in the first and second extracellular loops (especially the former) had reduced activity on a background of TSHR287–371. In summary, our data support the concept that the TSHR hinge contributes significantly to ligand binding affinity and signal transduction. Residues within the hinge, particularly between positions 371–384, appear involved in ectodomain inverse agonist activity. In addition, the hinge is necessary for functionality of activating mutations in the first and second extracellular loops. Rather than being an inert linker between the leucine-rich and transmembrane domains, the TSHR hinge is a signaling-specificity domain.

This article has been cited by other articles:

				C.-R. Chen, S. M. McLachlan, and B. Rapoport A Monoclonal Antibody with Thyrotropin (TSH) Receptor Inverse Agonist and TSH Antagonist Activities Binds to the Receptor Hinge Region as Well as to the Leucine-Rich Domain Endocrinology, July 1, 2009; 150(7): 3401 - 3408. [Abstract] [Full Text] [PDF]

				S. Mueller, G. Kleinau, M. W. Szkudlinski, H. Jaeschke, G. Krause, and R. Paschke The Superagonistic Activity of Bovine Thyroid-stimulating Hormone (TSH) and the Human TR1401 TSH Analog Is Determined by Specific Amino Acids in the Hinge Region of the Human TSH Receptor J. Biol. Chem., June 12, 2009; 284(24): 16317 - 16324. [Abstract] [Full Text] [PDF]

				R Nunez Miguel, J Sanders, D Y Chirgadze, J Furmaniak, and B Rees Smith Thyroid stimulating autoantibody M22 mimics TSH binding to the TSH receptor leucine rich domain: a comparative structural study of protein-protein interactions J. Mol. Endocrinol., May 1, 2009; 42(5): 381 - 395. [Abstract] [Full Text] [PDF]

				G. Kleinau and G. Krause Thyrotropin and Homologous Glycoprotein Hormone Receptors: Structural and Functional Aspects of Extracellular Signaling Mechanisms Endocr. Rev., April 1, 2009; 30(2): 133 - 151. [Abstract] [Full Text] [PDF]

				S. Sura-Trueba, C. Aumas, A. Carre, S. Durif, J. Leger, M. Polak, and N. de Roux An Inactivating Mutation within the First Extracellular Loop of the Thyrotropin Receptor Impedes Normal Posttranslational Maturation of the Extracellular Domain Endocrinology, February 1, 2009; 150(2): 1043 - 1050. [Abstract] [Full Text] [PDF]

				G. Agrawal and R. R. Dighe Critical Involvement of the Hinge Region of the Follicle-stimulating Hormone Receptor in the Activation of the Receptor J. Biol. Chem., January 30, 2009; 284(5): 2636 - 2647. [Abstract] [Full Text] [PDF]

				M. Bruysters, M. Verhoef-Post, and A. P. N. Themmen Asp330 and Tyr331 in the C-terminal Cysteine-rich Region of the Luteinizing Hormone Receptor Are Key Residues in Hormone-induced Receptor Activation J. Biol. Chem., September 19, 2008; 283(38): 25821 - 25828. [Abstract] [Full Text] [PDF]

				R Nunez Miguel, J Sanders, D Y Chirgadze, T L Blundell, J Furmaniak, and B Rees Smith FSH and TSH binding to their respective receptors: similarities, differences and implication for glycoprotein hormone specificity J. Mol. Endocrinol., September 1, 2008; 41(3): 145 - 164. [Abstract] [Full Text] [PDF]

				C.-R. Chen, S. M. McLachlan, and B. Rapoport Identification of Key Amino Acid Residues in a Thyrotropin Receptor Monoclonal Antibody Epitope Provides Insight into Its Inverse Agonist and Antagonist Properties Endocrinology, July 1, 2008; 149(7): 3427 - 3434. [Abstract] [Full Text] [PDF]