title: The third exoplasmic loop of the thyrotropin receptor is partially involved in signal transduction.
abstract: We characterized the role of the three exoplasmic loops in the transmembrane region of the thyrotropin receptor (TSHR) by substituting each loop with the counterpart of beta 2-adrenergic receptor amino acid sequence. Mutant El3 with a substitution of the 3rd exoplasmic loop showed significant decrease in the maximal level and sensitivity of TSH-stimulated cAMP response despite good retention of TSH binding. These findings suggest that the third exoplasmic loop of the TSH receptor is partially involved in the signal transduction mechanism.
authors.affiliation: Department of Laboratory Medicine, Kyoto University School of Medicine, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Kosugi
authors.forename: T
authors.initials: T
authors.lastname: Mori
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000242:Cyclic AMP / Q000378:metabolism; D004252:DNA Mutational Analysis; D007295:Inositol Phosphates / Q000378:metabolism; D008969:Molecular Sequence Data; D016296:Mutagenesis; D051381:Rats; D018343:Receptors, Adrenergic, beta-2 / Q000235:genetics; D011989:Receptors, Thyrotropin / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D015398:Signal Transduction; D013329:Structure-Activity Relationship; D013972:Thyrotropin / Q000378:metabolism; D014162:Transfection
chemical_list: D007295:Inositol Phosphates; D018343:Receptors, Adrenergic, beta-2; D011989:Receptors, Thyrotropin; D011994:Recombinant Proteins; D013972:Thyrotropin; D000242:Cyclic AMP