Molecular Cloning of the Thyrotropin Receptor

Abstract

The pituitary hormone thyrotropin, or thyroid-stimulating hormone (TSH), is the main physiological agent that regulates the thyroid gland. The thyrotropin receptor (TSHR) was cloned by selective amplification with the polymerase chain reaction of DNA segments presenting sequence similarity with genes for G protein-coupled receptors. Out of 11 new putative receptor clones obtained from genomic DNA, one had sequence characteristics different from all the others. Although this clone did not hybridize to thyroid transcripts, screening of a dog thyroid complementary DNA (cDNA) library at moderate stringency identified a cDNA encoding a 4.9-kilobase thyroid-specific transcript. The polypeptide encoded by this thyroid-specific transcript consisted of a 398-amino acid residue amino-terminal segment, constituting a putative extracellular domain, connected to a 346-residue carboxyl-terminal domain that contained seven putative transmembrane segments. Expression of the cDNA conferred TSH responsiveness to Xenopus oocytes and Y1 cells and a TSH binding phenotype to COS cells. The TSHR and the receptor for luteinizing hormone-choriogonadotropin constitute a subfamily of G protein-coupled receptors with distinct sequence characteristics.

Differential expression of the thyrostimulin subunits, glycoprotein 2 and 5 in the rat pituitary

“…In the same cell line, we have also monitored [Ca 2C ] i in response to TSH or recombinant proteins. The EC 50 values of bTSH were 0$3 nM for cAMP accumulation and 3$83 nM for Ca 2C mobilization (Table 3) that are compatible with a previous report (Nagayama et al 1989, Parmentier et al 1989. FLAGtagged rat and human thyrostimulin exhibited EC 50 s similar to that of bTSH but the magnitudes of their responses were w70% that of bTSH.…”

c-Kit Proto-oncogene Is More Likely to Lose Expression in Differentiated Thyroid Carcinoma Than Three Thyroid-specific Genes: Thyroid Peroxidase, Thyroglobulin, and Thyroid Stimulating Hormone Receptor.

“…The human thyrogrobulin cDNA probe was a 0.96 kb Barn HI-Pst I fragment obtained from JCRB (Japanese Cancer Research Resources Bank) [20]. The human TSH-R cDNA probe was a 2.3 kb Xho I-Barn HI fragment (courtesy of Prof. G. Vassart, Universite Libre de Bruxelles, Belgium) [21]. Both a 3.8 kb Hind III-Hind III human c-kit cDNA fragment [1] and a 0.4 kb EcoR I-EcoR I human f3-actin cDNA fragment [22] were kindly given by Dr. S. Tohda (Tokyo Medical & Dental University, Japan).…”

Targeting the TSH receptor in thyroid cancer

“…TSHR is encoded by the gene, thyroid-stimulating hormone receptor (TSHR), located on chromosome 14q31 and first cloned in 1989 (Parmentier et al 1989). Although encoded by a single gene, the gene product undergoes post-translational cleavage into an extracellular A-subunit and a largely intracellular B-subunit linked by disulfide bonds, with the exclusion of a 50 amino acid C-peptide region (Rapoport & McLachlan 2016).…”