The first cytoplasmic loop of the thyrotropin receptor is important for phosphoinositide signaling but not for agonist‐induced adenylate cyclase activation
- 21 March 1994
- journal article
- Published by Wiley in FEBS Letters
- Vol. 341 (2-3) , 162-166
- https://doi.org/10.1016/0014-5793(94)80449-4
Abstract
We investigated the role of the 1st cytoplasmic loop of the thyrotropin receptor (TSHR) on signal transduction using mutants as we did the 2nd and 3rd cytoplasmic loops [Kosugi S. et al. (1994) Mol. Endocrinol., in press; and 7, 1009‐1020]. Five substitution mutants involving the first cytoplasmic loop showed a TSH‐ or Graves' IgG‐stimulated cAMP response despite the low TSH binding B max. All the mutants completely lost or markedly decreased the TSH‐ or Graves' IgG‐stimulated inositol phosphate increase. These findings suggest that the l st cytoplasmic loop of the TSHR does not play a crucial role in agonist‐induced adenylate cyclase activation but that it is important for phosphoinositide signaling.Keywords
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