This Article Full Text Full Text (PDF) Purchase Article View Shopping Cart 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 Fares, F. A. Articles by Boime, I. Search for Related Content PubMed PubMed Citation Articles by Fares, F. A. Articles by Boime, I.

Conversion of Thyrotropin Heterodimer to a Biologically Active Single-Chain¹

Department of Biochemistry (F.A.F.), Carmel Medical Center, and the Rappaport Family Institute for Research in the Medical Sciences, Faculty of Medicine, Technion-Israel Institute of Technology, Haifa 34362, Israel; Department of Molecular Biology and Pharmacology (D.B.-M., M.P., I.B.), Washington University School of Medicine, St. Louis, Missouri 63110; and Division of Reproductive Medicine (S.Y., A.J.W.H.), Department of Gynecology and Obstetrics, Stanford University Medical Center, Stanford, California 94305

Address all correspondence and requests for reprints to: Dr. Fuad A. Fares, Department of Biochemistry, Carmel Medical Center, Haifa 34362, Israel. E-mail: biochem{at}actcom.co.il

TSH and the gonadotropins, FSH, LH, and CG are a family of heterodimeric glycoprotein hormones composed of a common -subunit noncovalently linked to a hormone specific ß-subunit. Assembly of - and ß-subunits is essential for hormone-specific posttranslational modifications, receptor binding, and bioactivity. Structure-function studies of TSH and gonadotropins using site-directed mutagenesis can often affect folding, assembly, and secretion of the hormone. To circumvent these difficulties, recently, the gonadotropin heterodimers were converted to single chains. Here we converted the hTSH heterodimer to a biologically active single chain by genetically fusing the amino terminal end of the common -subunit to the carboxyl terminal end of hTSHß in the presence or absence of hCGß carboxyl terminal peptide (CTP), which was used as a linker. Wild-type hTSH and the single chains were expressed in Chinese hamster ovary (CHO) cells, and they were efficiently secreted. Although the secretion rate of the single chain was 3-fold higher than that of hTSH wild-type. Moreover, the secretion of the single chain in the presence of the CTP linker was dramatically increased. On the other hand, receptor binding and in vitro bioactivity of the single chains were similar to that of hTSH wild-type. These data indicate the potential of the single chain approach to further investigate structure-function relationships of TSH.

This article has been cited by other articles:

				S. Legardinier, J.-C. Poirier, D. Klett, Y. Combarnous, and C. Cahoreau Stability and biological activities of heterodimeric and single-chain equine LH/chorionic gonadotropin variants J. Mol. Endocrinol., April 1, 2008; 40(4): 185 - 198. [Abstract] [Full Text] [PDF]

				N. Azzam, R. Bar-Shalom, Z. Kraiem, and F. Fares Human Thyrotropin (TSH) Variants Designed by Site-Directed Mutagenesis Block TSH Activity in Vitro and in Vivo Endocrinology, June 1, 2005; 146(6): 2845 - 2850. [Abstract] [Full Text] [PDF]

				V. Garcia-Campayo, I. Boime, X. Ma, D. Daphna-Iken, and T. R. Kumar A Single-Chain Tetradomain Glycoprotein Hormone Analog Elicits Multiple Hormone Activities In Vivo Biol Reprod, February 1, 2005; 72(2): 301 - 308. [Abstract] [Full Text] [PDF]

				R. L. Schubert, P. Narayan, and D. Puett Specificity of Cognate Ligand-Receptor Interactions: Fusion Proteins of Human Chorionic Gonadotropin and the Heptahelical Receptors for Human Luteinizing Hormone, Thyroid-Stimulating Hormone, and Follicle-Stimulating Hormone Endocrinology, January 1, 2003; 144(1): 129 - 137. [Abstract] [Full Text] [PDF]

				V. Garcia-Campayo, T. R. Kumar, and I. Boime Thyrotropin, Follitropin, and Chorionic Gonadotropin Expressed as a Single Multifunctional Unit Reveal Remarkable Permissiveness in Receptor-Ligand Interactions Endocrinology, October 1, 2002; 143(10): 3773 - 3778. [Abstract] [Full Text] [PDF]

				F. A. Fares, F. Levi, A. Z. Reznick, and Z. Kraiem Engineering a Potential Antagonist of Human Thyrotropin and Thyroid-stimulating Antibody J. Biol. Chem., February 9, 2001; 276(7): 4543 - 4548. [Abstract] [Full Text] [PDF]

				D. Ben-Menahem, A. Jablonka-Shariff, R. K. Hyde, M. R. Pixley, S. Srivastava, P. Berger, and I. Boime The Position of the alpha and beta Subunits in a Single Chain Variant of Human Chorionic Gonadotropin Affects the Heterodimeric Interaction of the Subunits and Receptor-binding Epitopes J. Biol. Chem., August 3, 2001; 276(32): 29871 - 29879. [Abstract] [Full Text] [PDF]