help button home button Endocrine Society Endocrinology
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
This Article
Right arrow Abstract Freely available
Right arrow Full Text (PDF)
Right arrow Purchase Article
Right arrow View Shopping Cart
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow Request Copyright Permission
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Chazenbalk, G. D.
Right arrow Articles by Rapoport, B.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Chazenbalk, G. D.
Right arrow Articles by Rapoport, B.
Endocrinology Vol. 140, No. 10 4516-4520
Copyright © 1999 by The Endocrine Society

ARTICLES

On the Functional Importance of Thyrotropin Receptor Intramolecular Cleavage1

Gregorio D. Chazenbalk, Kunihiko Tanaka, Sandra M. McLachlan and Basil Rapoport

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

Address all correspondence and requests for reprints to: Basil Rapoport, M.B., Cedars-Sinai Medical Center, 8700 Beverly Boulevard, Suite B-131, Los Angeles, California 90048.


   Abstract
Top
 Abstract
Introduction
 Materials and Methods
 Results
 Discussion
 References
 
We examined the relationship between TSH receptor (TSHR) cleavage into two subunits and ligand-independent, constitutive activity characteristic of this receptor. Because of homology to the thrombin receptor-tethered ligand, we focused initially on a region in the vicinity of the second, downstream cleavage site of the TSHR ectodomain. We introduced into the wild-type TSHR three mutations. One mutation, TSHR(GQE367–369NET) prevents cleavage at site 2. The other two mutations, ELK369–371T-Y (TSHR-E1a2) and NPQE372–375SAIF (TSHR-E1b), introduce major changes into the potential tethered ligand. Basal, steady state intracellular cAMP levels in cloned, stably transfected Chinese hamster ovary cells were expressed as a function of the number of receptors (cAMP/receptor). None of these three mutations decreased ligand-independent constitutive activity, thereby excluding the tethered ligand hypothesis as well as a requirement for cleavage at site 2 in this process. Turning to the more upstream site 1 in the TSHR ectodomain, we examined a receptor (TSHR-{Delta}50AA) with deletion of a unique 50-amino acid insertion (residues 317–366) that appears to be involved in cleavage at this site. Constitutive cAMP production was similar to that of the wild-type TSHR. Finally, we studied a TSHR mutant that cleaves at neither site 1 (deletion of residues 317–366) nor site 2 (GQE367–369NET substitution) and, therefore, does not cleave into A and B subunits. Again, the basal, constitutive level of cAMP production was similar to that of the wild-type TSHR.

In summary, contrary to the prevailing hypothesis based on several lines of evidence, TSHR cleavage into subunits is not associated with constitutive, ligand-independent activity.


   Introduction
Top
 Abstract
 Introduction
Materials and Methods
 Results
 Discussion
 References
 
THE TSH RECEPTOR (TSHR) is unique among the glycoprotein hormone receptors in that some mature receptors on the cell surface cleave into two subunits (1, 2, 3). After cleavage, an extracellular A subunit remains linked by disulfide bonds to a largely transmembrane B subunit. Not all TSHR on the cell surface cleave into two subunits. As detected by TSH cross-linking to intact cells, two TSHR populations are evident, a single chain form as well as the cleaved molecule (2). Recently, it has been determined that intramolecular cleavage involves the removal of a segment of the ectodomain (4, 5), with further evidence suggesting that cleavage occurs at two sites (6, 7). Alternatively, cleavage at upstream site 1 is followed by excision of the intervening polypeptide segment downstream to site 2 (5).

The functional significance of TSHR intramolecular cleavage is an enigma. Cleavage is not necessary for hormone binding; TSH binds to both cleaved and uncleaved forms of the TSHR with similar high affinity (2). Unlike thrombin and its cognate receptor (8), TSH does not cleave the TSHR; cleavage occurs in nonthyroidal cells never exposed to TSH (2, 3). Moreover, TSH action does not require a cleaved receptor. Thus, TSH can activate chimeric TSH-LH receptors that do not cleave into two subunits (9, 10). Another unusual feature of the TSHR is that, unlike the noncleaving gonadotropin receptors, it is "noisy," transducing a modest signal via adenylate cyclase even in the absence of ligand (11, 12, 13, 14).

The combination of intramolecular cleavage and constitutive, ligand-independent activity has raised the possibility that these two features are interrelated. Indeed, strong circumstantial evidence supports this concept: 1) cleavage activates the thrombin receptor, another member of the G protein-coupled receptor superfamily (8); 2) light trypsinization of cells expressing the TSHR is reported to activate the receptor (15), and trypsin converts monomeric TSHR on the cell surface into the two-subunit form (7); 3) the carboxyl-terminal region of the TSHR ectodomain involved in intramolecular cleavage plays a role in signal transduction (16, 17); and 4) also in the regions of TSHR cleavage, spontaneous mutation of Ser281 (18, 19) and deletion by mutagenesis of residues 339–367 (20) increase constitutive activity. Based on this evidence, in the present study we tested the hypothesis that TSHR cleavage enhances ligand-independent activity.


   Materials and Methods
Top
 Abstract
 Introduction
 Materials and Methods
Results
 Discussion
 References
 
Construction and expression of TSHR mutants
Plasmids for TSHR mutants were constructed as follows.

E1a1, E1a2, and E1b. Three series of mutations (GQE367–369NET, ELK369–371T-Y, and NPQE372–375SAIF, respectively), previously introduced into chimeric receptor TSH-LHR-4 (6, 16), were transferred into the wild-type TSHR complementary DNA (cDNA) with 5'- and 3'-untranslated regions deleted in the eukaryotic expression vector pECE-NEO (21, 22). To accomplish this, we replaced the MluI-EcoRV fragment (domains C and D) of the above constructs with the corresponding segment of the wild-type TSHR cDNA (21) modified by the introduction of MluI and EcoRV restriction sites (16).

E1a1-{Delta}50AA. Construction of this TSHR mutant, with deletion of amino acid residues 317–366 and a GQE367–369NET substitution, has been described previously (7).

Deletion mutant of residues 317–366 (TSHR-{Delta}50AA). The NET367–369GQE substitution in the above construct (E1a1-{Delta}50AA) was converted back to the wild-type (GQE) by PCR using overlapping primers and Pfu DNA polymerase (Stratagene, San Diego, CA).

The nucleotide sequences at the restriction junctions as well as those modified by mutagenesis were confirmed by dideoxynucleotide sequencing (23). Plasmids were subsequently stably transfected with Lipofectine (Life Technologies, Inc., Gaithersburg, MD) into Chinese hamster ovary (CHO) cells cultured in Ham’s F-12 medium supplemented with 10% FCS and standard antibiotics. Selection was performed with 400 µg/ml G418 (Life Technologies, Inc.). Individual clones were isolated by limiting dilution and screened for [125I]TSH binding. For each mutant, a clone with high level TSHR expression was selected and propagated for further study.

TSH binding
Highly purified bovine TSH (5 µg; 30 U/mg protein) was radiolabeled with 125I to a specific activity of about 80 µCi/µg protein using Bolton-Hunter reagent (4400 Ci/mmol; NEN Life Science Products, Boston, MA) according to the protocol of the manufacturer, followed by Sephadex G-100 chromatography (24). In later experiments, [125I]TSH was purchased from Kronus (San Clemente, CA) or was a gift from B.R.A.H.M.S. (Berlin, Germany). CHO cells stably transfected with TSHR cDNA were grown to confluence in 24-well culture plates. Cells were then incubated for 2.5 h at 37 C in 250 µl binding buffer (Hanks’ buffer with 280 mM sucrose substituting for NaCl to maintain isotonicity and 0.25% BSA) containing approximately 10,000 cpm [125I]TSH in the presence or absence of increasing concentrations of unlabeled bovine TSH (Sigma Chemical Co., St. Louis, MO). At the end of the incubation period, the cells were rapidly rinsed three times with binding buffer (4 C) and solubilized with 0.5 ml 1 N NaOH, and radioactivity was measured in a {gamma}-counter. Experiments using increasing concentrations of [125I]TSH were performed in cells cultured under the same conditions except that no unlabeled TSH was added. Nonspecific 125I binding to untransfected CHO cells was subtracted from total counts bound to provide specific counts bound.

TSH stimulation of intracellular cAMP
Transfected CHO cells, grown to confluence in 24-well plates, were incubated for 2 h at 37 C in Ham’s F-12 medium containing 1% BSA and 1 mM isobutylmethylxanthine, with or without added bovine TSH (Sigma Chemical Co.). The medium was then aspirated, and intracellular cAMP was extracted with 95% ethanol, evaporated to dryness, and resuspended in 50 mM sodium acetate, pH 6.2. cAMP was measured by RIA using cAMP, 2'-O-Succinyl-[125I]iodotyrosine methyl ester (NEN Life Science Products), and a rabbit anti-cAMP antibody from Fitzgerald (Concord, MA).


   Results
Top
 Abstract
 Introduction
 Materials and Methods
 Results
Discussion
 References
 
TSHR ectodomain cleavage at site 2
Cleavage by thrombin of the thrombin receptor exposes a new N-terminus that functions as a tethered ligand (8). This report initially raised the possibility that the TSHR contained a similar sequence. However, none was apparent on a computer homology search. The recent observation that TSHR cleavage at downstream site 2 could be abolished by substitution of amino acid residues 367–369 with the homologous residues of the noncleaving LH/CG receptor (6) induced us to focus again on this region without computer assistance. Although the above substitutions localize a cleavage region rather than the precise cleavage site, we noted that directly downstream of TSHR residues 367–369 are six amino acids with homology (three identical, three highly conserved) to the thrombin receptor tethered ligand (Fig. 1AGo). We, therefore, tested the hypothesis that ligand-independent TSHR cleavage at site 2 exposes a tethered ligand that could explain the elevated constitutive activity of this receptor.



View larger version (18K):
[in this window]
[in a new window]
  		Figure 1. A, Homology between a TSHR region related to cleavage at site 2 and the thrombin receptor-tethered ligand. Substitution of TSHR residues GQE367–369 with the corresponding region of the noncleaving LH/CG receptor abrogates cleavage at site 2 (6 ). Directly downstream of this site are six amino acids homologous (three identical, three conserved) to the thrombin receptor (boxed). The arrow indicates the site at which thrombin cleaves its cognate receptor, residue 42 becoming the amino-terminus of the tethered ligand that activates this receptor (8 ). B, Mutations introduced into the TSHR region with homology to the thrombin receptor-tethered ligand. Substitutions are the corresponding residues in the homologous LH/CG receptor. In TSHR-E1a2, the dash indicates that only two amino acid residues in the LH/CG receptor correspond to the triplet in the TSHR. TSHR-E1a1 is shown in bold because its mutation prevents cleavage at site 2.

 
Activity of a tethered ligand immediately downstream of cleavage site 2 could be prevented by 1) abrogating cleavage at site 2 or, 2) altering the amino acids in the tethered ligand. We, therefore, introduced into the wild-type TSHR three mutations previously created on a background of a TSH-LH/CG chimeric receptor (6) (Fig. 1BGo). One mutation, GQE367–369NET (also termed E1a1 based on previous chimeric constructs) (17), contains the LH/CG receptor substitution that prevents cleavage at site 2. The other two mutations, ELK369–371T-Y (TSHR-E1a2) and NPQE372–371SAIF (TSHR-E1b), do not prevent cleavage at site 2, but introduce major changes into a potential tethered ligand.

Functional studies of these three mutant TSHR were performed using an approach to compensate for variable levels of TSHR expression obtained with transient and stable transfections. For each mutant, we established a clonal, stably transfected CHO cell line and determined the number of TSH-binding sites by Scatchard analysis (25) (Table 1Go). Basal, steady state intracellular cAMP levels could then be expressed as a function of the number of cell surface receptors (cAMP/receptor). As as basis for this calculation, proportionality has previously been demonstrated between the level of TSHR expression and cAMP generation in intact cells (11, 26). CHO cells expressing the wild-type TSHR had basal cAMP levels (after subtraction of cAMP levels in untransfected cells) of 13.2 fmol cAMP/fmol TSH receptor (Table 1Go). Mutants TSHR-E1a1, TSHR-E1a2, and TSHR-E1b all had basal levels of cAMP similar to those of the wild-type TSHR, indicating that the tethered ligand hypothesis was incorrect.


View this table:
[in this window]
[in a new window]
  		Table 1. Basal, ligand-independent cAMP levels in TSH receptor mutants

 
TSHR ectodomain cleavage at site 1
We next examined the relationship between cleavage at upstream site 1 in the TSHR ectodomain and constitutive receptor activity. Relative to the noncleaving LH/CG receptor, the TSHR ectodomain contains a unique 50-amino acid insertion (Fig. 2Go). Deletion of this region does not significantly alter TSH binding or TSH-mediated cAMP generation (27), but does prevent cleavage at site 1 (7). In the present study, we studied basal, ligand-independent cAMP levels in cells expressing this mutant receptor (TSHR-{Delta}50AA). Constitutive cAMP production was similar to that of the wild-type TSHR (Table 1Go).



View larger version (21K):
[in this window]
[in a new window]
  		Figure 2. TSHR mutations that prevent intramolecular cleavage at sites 1 and 2. Relative to the noncleaving LH/CG receptor, the TSHR ectodomain contains a unique 50-amino acid insertion, whose deletion prevents cleavage at site 1, but not at site 2 (7 ). Evidence suggests that site 1 is in the region between the N-linked glycosylation moiety at residue 302 and residue 317, the N-terminus of the 50-amino acid insertion (7 ). The substitution (GQE367–369NET) that abrogates cleavage at site 2, but not site 1, is described in Fig 1Go.

 
Basal cAMP generation in a noncleaving TSHR
Finally, despite the above data, there was still circumstantial evidence (see above) that cleavage into two subunits could lead to increased TSHR constitutive activity. We, therefore, examined this parameter in cells expressing a TSHR that does not cleave into A and B subunits (7). This receptor, {Delta}50AA-E1a1, contains both the 50-amino acid deletion of residues 317–366 and the E1a1 (GQE367–369NET) substitution, thereby eliminating both cleavage sites (Fig. 2Go). Again, the basal, constitutive level of cAMP production was similar to the level in wild-type TSHR (Table 1Go).

TSH-induced cAMP responses
Although the above data established that TSHR cleavage did not influence ligand-independent constitutive activity, it remained possible that receptor cleavage could influence the cAMP response to TSH stimulation. This was not the case. The TSH concentrations required for half-maximal stimulation (EC50) were not significantly different between any of the TSHR mutants (range, 0.8–2.0 mU TSH/ml) and the wild-type TSHR (1.0 ± 0.2 mU TSH/ml; mean ± SE; n = 3).


   Discussion
Top
 Abstract
 Introduction
 Materials and Methods
 Results
 Discussion
References
 
Considerable circumstantial evidence, described above, has pointed toward an association between two unique features of the TSHR, namely proteolytic cleavage into subunits (1, 2, 3) and a high level of ligand-independent cAMP generation (11, 12, 13, 14). Therefore, the present data clearly showing that this association does not exist are both surprising and important. This observation now joins a list of other phenomena previously shown not to be associated with TSHR cleavage into two subunits. Thus, TSHR cleavage: 1) is not required for high affinity TSH binding (2), 2) is unnecessary for TSH activation of the receptor (9, 10), and 3) is unrelated to the ligand-independent "noisiness" of the TSHR (present study).

What, then, is the functional significance of TSHR cleavage? The fact that the other glycoprotein hormone receptors do not cleave into subunits suggests that this phenomenon is not simply an unimportant curiosity. Future studies will be needed to test the hypothesis that the two-subunit and single chain TSHR have different intracellular trafficking pathways. For example, the two-subunit receptor could preferentially traffic to endosomes, whereas the internalized single chain receptor could recycle to the plasma membrane. The unique, spontaneous occurrence of disease-causing autoantibodies to the TSHR may also be a consequence of TSHR cleavage, for example related to the release of a C peptide.

In summary, a number of attractive hypotheses exist that suggest a physiological role for TSHR intramolecular cleavage into two subunits. Progressively, these are being eliminated. The present study excludes a hypothesis to which available evidence was strongly pointing, namely that cleavage increases constitutive, ligand-independent TSHR activity.


   Acknowledgments
 
We thank the National Hormone and Distribution Program, the NIDDK, the Center for Population Research of the NICHHD, the Agricultural Research Service of the USDA, and the University of Maryland School of Medicine for kindly providing the highly purified bovine TSH for radioiodination. We are also grateful to Dr. Joachim Struck of B.R.A.H.M.S. (Berlin Germany) for providing radiolabeled TSH.


   Footnotes
 
1 This work was supported by NIH Grant DK-19289. Back

Received March 23, 1999.


   References
Top
 Abstract
 Introduction
 Materials and Methods
 Results
 Discussion
 References
 

  1. Buckland PR, Rickards CR, Howells RD, Jones ED, Rees Smith B 1982 Photo-affinity labelling of the thyrotropin receptor. FEBS Lett 145:245–249[CrossRef]
  2. Russo D, Chazenbalk GD, Nagayama Y, Wadsworth HL, Seto P, Rapoport B 1991 A new structural model for the thyrotropin (TSH) receptor as determined by covalent crosslinking of TSH to the recombinant receptor in intact cells: evidence for a single polypeptide chain. Mol Endocrinol 5:1607–1612[Abstract]
  3. Loosfelt H, Pichon C, Jolivet A, Misrahi M, Caillou B, Jamous M, Vannier B, Milgrom E 1992 Two-subunit structure of the human thyrotropin receptor. Proc Natl Acad Sci USA 89:3765–3769[Abstract/Free Full Text]
  4. Chazenbalk GD, Tanaka K, Nagayama Y, Kakinuma A, Jaume JC, McLachlan SM, Rapoport B 1997 Evidence that the thyrotropin receptor ectodomain contains not one, but two, cleavage sites. Endocrinology 138:2893–2899[Abstract/Free Full Text]
  5. de Bernard S, Misrahi M, Huet J-C, Beau I, Desroches A, Loosfelt H, Pichon C, Pernollet J-C, Milgrom E 1999 Sequential cleavage and excision of a segment of the thyrotropin receptor ectodomain. J Biol Chem 274:101–107[Abstract/Free Full Text]
  6. Kakinuma A, Chazenbalk GD, Tanaka K, Nagayama Y, McLachlan SM, Rapoport B 1997 An N-linked glycosylation motif from the non-cleaving luteinizing hormone receptor substituted for the homologous region (Gly-367 to Glu-369) of the thyrotropin receptor prevents cleavage at its second, downstream site. J Biol Chem 272:28296–28300[Abstract/Free Full Text]
  7. Tanaka K, Chazenbalk GD, McLachlan SM, Rapoport B 1998 Thyrotropin receptor cleavage at site 1 does not involve a specific amino acid motif but instead depends on the presence of the unique, 50 amino acid insertion. J Biol Chem 273:1959–1963[Abstract/Free Full Text]
  8. Vu TK, Hung DT, Wheaton VI, Coughlin SR 1991 Molecular cloning of a functional thrombin receptor reveals a novel proteolytic mechanism of receptor activation. Cell 64:1057–1068[CrossRef][Medline]
  9. Nagayama Y, Russo D, Chazenbalk GD, Wadsworth HL, Rapoport B 1990 Extracellular domain chimeras of the TSH and LH/CG receptors reveal the mid-region (amino acids 171–260) to play a vital role in high affinity TSH binding. Biochem Biophys Res Commun 173:1150–1156[CrossRef][Medline]
  10. Chazenbalk GD, McLachlan SM, Nagayama Y, Rapoport B 1996 Is receptor cleavage into two subunits necessary for thyrotropin action? Biochem Biophys Res Commun 225:479–484[CrossRef][Medline]
  11. Van Sande J, Swillens S, Gerard C, Allgeier A, Massart C, Vassart G, Dumont J 1995 In Chinese hamster ovary K1 cells dog and human thyrotropin receptors activate both the cyclic AMP and the phosphatidylinositol 4,5-bisphosphate cascades in the presence of thyrotropin and the cyclic AMP cascade in its absence. Eur J Biochem 229:338–343[Medline]
  12. Van Sande J, Parma J, Tonacchera M, Swillens S, Dumont J, Vassart G 1995 Genetic basis of endocrine disease: somatic and germline mutations of the TSH receptor gene in thyroid diseases. J Clin Endocrinol Metab 80:2577–2585[CrossRef][Medline]
  13. Parma J, Van Sande J, Swillens S, Tonacchera M, Dumont J, Vassart G 1995 Somatic mutations causing constitutive activity of the thyrotropin receptor are the major cause of hyperfunctioning thyroid adenomas: Identification of additional mutations activating both the cyclic adenosine 3',5'-monophosphate and inositol phosphate-Ca2+ cascades. Mol Endocrinol 9:725–733[Abstract]
  14. Kosugi S, Mori T 1995 TSH receptor and LH receptor. Endocr J 42:587–606[Medline]
  15. Van Sande J, Massart C, Costagliola S, Allgeier A, Cetani F, Vassart G, Dumont JE 1996 Specific activation of the thyrotropin receptor by trypsin. Mol Cell Endocrinol 119:161–168[CrossRef][Medline]
  16. Nagayama Y, Wadsworth HL, Chazenbalk GD, Russo D, Seto P, Rapoport B 1991 Thyrotropin-luteinizing hormone/chorionic gonadotropin receptor extracellular domain chimeras as probes for TSH receptor function. Proc Natl Acad Sci USA 88:902–905[Abstract/Free Full Text]
  17. Nagayama Y, Rapoport B 1992 Role of the carboxyl-terminal half of the extracellular domain of the human thyrotropin receptor in signal transduction. Endocrinology 131:548–552[Abstract]
  18. Duprez L, Parma J, Costagliola S, Hermans J, Van Sande J, Dumont J, Vassart G 1997 Constitutive activation of the TSH receptor by spontaneous mutations affecting the N-terminal extracellular domain. FEBS Lett 409:469–474[CrossRef][Medline]
  19. Kopp P, Muirhead S, Jourdain N, Gu W-X, Jameson JL, Rodd C 1997 Congenital hyperthyroidism caused by a solitary toxic adenoma harboring a novel somatic mutation (serine281-isoleucine) in the extracellular domain of the thyrotropin receptor. J Clin Invest 100:1634–1639[Medline]
  20. Zhang M-L, Sugawa H, Kosugi S, Mori T 1995 Constitutive activation of the thyrotropin receptor by deletion of a portion of the extracellular domain. Biochem Biophys Res Commun 211:205–210[CrossRef][Medline]
  21. Nagayama Y, Kaufman KD, Seto P, Rapoport B 1989 Molecular cloning, sequence and functional expression of the cDNA for the human thyrotropin receptor. Biochem Biophys Res Commun 165:1184–1190[CrossRef][Medline]
  22. Kakinuma A, Chazenbalk G, Filetti S, McLachlan SM, Rapoport B 1996 Both the 5' and 3' non-coding regions of the thyrotropin receptor messenger RNA influence the level of receptor protein expression in transfected mammalian cells. Endocrinology 137:2664–2669[Abstract]
  23. Sanger F, Nicklen S, Coulson AR 1977 DNA sequencing with chain terminating inhibitors. Proc Natl Acad Sci USA 74:5463–5467[Abstract/Free Full Text]
  24. Goldfine ID, Amir SM, Petersen AW, Ingbar SH 1974 Preparation of biologically active 125I-TSH. Endocrinology 95:1228–1233[Medline]
  25. Scatchard G 1949 The attractions of proteins for small molecules and ions. Ann NY Acad Sci 51:660–672[CrossRef]
  26. Chazenbalk GD, Kakinuma A, Jaume JC, McLachlan SM, Rapoport B 1996 Evidence for negative cooperativity among human thyrotropin receptors overexpressed in mammalian cells. Endocrinology 137:4586–4591[Abstract]
  27. Wadsworth HL, Chazenbalk GD, Nagayama Y, Russo D, Rapoport B 1990 An insertion in the human thyrotropin receptor critical for high affinity hormone binding. Science 249:1423–1425[Abstract/Free Full Text]



This article has been cited by other articles:


Home page
 Mol. Endocrinol.Home page
Y. Mizutori, C.-R. Chen, S. M. McLachlan, and B. Rapoport
The Thyrotropin Receptor Hinge Region Is Not Simply a Scaffold for the Leucine-Rich Domain but Contributes to Ligand Binding and Signal Transduction
Mol. Endocrinol., May 1, 2008; 22(5): 1171 - 1182.
[Abstract] [Full Text] [PDF]

Home page
 J EndocrinolHome page
T. Ando, R. Latif, and T. F Davies
Antibody-induced modulation of TSH receptor post-translational processing
J. Endocrinol., October 1, 2007; 195(1): 179 - 186.
[Abstract] [Full Text] [PDF]

Home page
 EndocrinologyHome page
C.-R. Chen, G. D. Chazenbalk, K. A. Wawrowsky, S. M. McLachlan, and B. Rapoport
Evidence that Human Thyroid Cells Express Uncleaved, Single-Chain Thyrotropin Receptors on Their Surface
Endocrinology, June 1, 2006; 147(6): 3107 - 3113.
[Abstract] [Full Text] [PDF]

Home page
 EndocrinologyHome page
R. Latif, T. Ando, and T. F. Davies
Monomerization as a Prerequisite for Intramolecular Cleavage and Shedding of the Thyrotropin Receptor
Endocrinology, December 1, 2004; 145(12): 5580 - 5588.
[Abstract] [Full Text] [PDF]

Home page
 J. Biol. Chem.Home page
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]

Home page
 EndocrinologyHome page
G. D. Chazenbalk, C.-R. Chen, S. M. McLachlan, and B. Rapoport
Does Thyrotropin Cleave Its Cognate Receptor?
Endocrinology, January 1, 2004; 145(1): 4 - 10.
[Abstract] [Full Text] [PDF]

Home page
 EndocrinologyHome page
I. Ciullo, R. Latif, P. Graves, and T. F. Davies
Functional Assessment of the Thyrotropin Receptor-{beta} Subunit
Endocrinology, July 1, 2003; 144(7): 3176 - 3181.
[Abstract] [Full Text] [PDF]

Home page
 EndocrinologyHome page
C.-R. Chen, G. D. Chazenbalk, S. M. McLachlan, and B. Rapoport
Targeted Restoration of Cleavage in a Noncleaving Thyrotropin Receptor Demonstrates that Cleavage Is Insufficient to Enhance Ligand-Independent Activity
Endocrinology, April 1, 2003; 144(4): 1324 - 1330.
[Abstract] [Full Text] [PDF]

Home page
 Mol. Endocrinol.Home page
N. Ghinea, C. Baratti-Elbaz, A. De Jesus-Lucas, and E. Milgrom
TSH Receptor Interaction with the Extracellular Matrix: Role on Constitutive Activity and Sensitivity to Hormonal Stimulation
Mol. Endocrinol., May 1, 2002; 16(5): 912 - 923.
[Abstract] [Full Text] [PDF]

Home page
 Mol. Endocrinol.Home page
H. Nikkila, D. R. McMillan, B. S. Nunez, L. Pascoe, K. M. Curnow, and P. C. White
Sequence Similarities between a Novel Putative G Protein-Coupled Receptor and Na+/Ca2+ Exchangers Define a Cation Binding Domain
Mol. Endocrinol., September 1, 2000; 14(9): 1351 - 1364.
[Abstract] [Full Text]

This Article
Right arrow Abstract Freely available
Right arrow Full Text (PDF)
Right arrow Purchase Article
Right arrow View Shopping Cart
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow Request Copyright Permission
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Chazenbalk, G. D.
Right arrow Articles by Rapoport, B.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Chazenbalk, G. D.
Right arrow Articles by Rapoport, B.

HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
Endocrinology Endocrine Reviews J. Clin. End. & Metab.
Molecular Endocrinology Recent Prog. Horm. Res. All Endocrine Journals