Bovine thyrotropin receptor cDNA is characterized by full-length and truncated transcripts

Abstract

The complete coding sequence for the bovine thyrotropin (TSH) receptor was derived using a modified PCR cloning strategy. The bovine thyrotropin receptor conforms to the pattern of receptor interacting with membrane-bound G-protein already established in other species for TSH and gonadotropins receptors. The cDNA for the bovine TSH receptor consists of an open reading frame 2289 nucleotides in length, corresponding to a protein of 763 amino acids (estimated molecular mass of 86.4 kDa) which includes a 20 amino acid putative leading signal peptide. The receptor consists of a large NH2-terminal extracellular membrane domain of 417 amino acids with 5 potential N-linked glycosylation sites, a transmembrane domain (265 amino acids) consisting of 7 putative membrane alpha-helix spanning segments, and an intracytoplasmic COOH-terminal domain (82 amino acids). The bovine TSH receptor is one amino acid less than the corresponding sequence in dog, human, rat and mouse. Cysteine residues (n = 22) were conserved when compared with other TSH receptors. Three potential phosphorylation sites were found in the transmembrane domain and the COOH-terminal domain. As with other members of this receptor family, alternative splicing was observed. A transcribed but truncated TSH receptor of 1769 nucleotides was demonstrated, lacking half of the V segment of the transmembrane domain up to the COOH-terminal domain of the full length TSH receptor. Additionally, alternative transcriptional start sites were observed. Northern blot analysis using a probe (1170 bp) spanning part of the extracellular domain up to the first loop of the transmembrane domain showed specific expression in the bovine thyroid gland with major transcripts of 9.3 and 4.3 kb, and a minor transcript of 3.8 kb being detected.

Sporadic Congenital Hyperthyroidism due to a Germline Mutation in the Thyrotropin Receptor Gene (Leu 512 Gln) in a Japanese Patient

“…Somatic mutations of residue 512 have been described in three cases of toxic thyroid nodules [ 13,14]; however, a germline mutation of this residue has not been reported previously in sporadic or familial cases of nonautoimmune hyperthyroidism. The third transmembrane domain of the TSHR from all mammalian species are identical amino acid sequences [15][16][17][18][19][20], and plays a key role in the activation of the receptor by a conformational change in coordination with seven transmembrane domains [21], suggesting the structural and/or functional importance of this domain of the TSHR. Indeed, the functionality of this mutated receptor was investigated by transient transfection in COS-7 cells.…”

Ανίχνευση Μεταλλάξεων Του Υποδοχέα Της Θυρεοειδοτρόπου Ορμόνης (TSH-R) Σε Αυτόνομα Αδενώματα Του Θυρεοειδούς

“…To cDNA του TSHR του κυνός κλωνοποιήθηκε με RT-PCR το 1989 (Parmentier 1989). Ακολούθως κλωνοποιήθηκαν οι υποδοχείς του ανθρώπου, του αρουραίου, του επίμυος, της αγελάδας, του προβάτου και της γαλής (Nagayama 1989, Akamizu 1990, Stein 1994, Gu 1995, Silversides 1997, Bockmann 1997, Nguyen 1998). H ομολογία ανάμεσα στα διάφορα είδη είναι πάνω από 90%.…”