TY - JOUR
T1 - A circulating, biologically inactive thyrotropin caused by a mutation in the beta subunit gene
AU - Medeiros-Neto, Geraldo
AU - Herodotou, Demetrios T.
AU - Rajan, Sabitha
AU - Kommareddi, Sitara
AU - De Lacerda, Luiz
AU - Sandrini, Romolo
AU - Boguszewski, Margaret C.S.
AU - Hollenberg, Anthony N.
AU - Radovick, Sally
AU - Wondisford, Fredric E.
PY - 1996/3/1
Y1 - 1996/3/1
N2 - Mutation of a critical carboxy-terminal cysteine residue (C105V) in the thyrotropin-β (TSH-β) subunit gene was found in two related families with central hypothyroidism. Affected patients had low thyroid hormone levels and radioactive iodine uptake in the thyroid gland associated with measurable serum TSH. Thyrotropin-releasing hormone-stimulated TSH secretion did not increase thyroid hormone production in these patients as compared to their unaffected siblings, suggesting that the mutant TSH was biologically inactive in vivo. Recombinant TSH harboring this mutation was confirmed to be biologically inactive in an in vitro bioassay. Based on crystallographic structure of chorionic gonadotropin, a disulfide bond between C19 and C105 in the TSH-β subunit is predicted to form the 'buckle' of a 'seat belt' that surrounds the common α subunit and maintains the conformation and bioactivity of the hormone. This natural mutation of the TSH-β subunit confirms the importance of the seat belt in the family of pituitary and placental glycoprotein hormones.
AB - Mutation of a critical carboxy-terminal cysteine residue (C105V) in the thyrotropin-β (TSH-β) subunit gene was found in two related families with central hypothyroidism. Affected patients had low thyroid hormone levels and radioactive iodine uptake in the thyroid gland associated with measurable serum TSH. Thyrotropin-releasing hormone-stimulated TSH secretion did not increase thyroid hormone production in these patients as compared to their unaffected siblings, suggesting that the mutant TSH was biologically inactive in vivo. Recombinant TSH harboring this mutation was confirmed to be biologically inactive in an in vitro bioassay. Based on crystallographic structure of chorionic gonadotropin, a disulfide bond between C19 and C105 in the TSH-β subunit is predicted to form the 'buckle' of a 'seat belt' that surrounds the common α subunit and maintains the conformation and bioactivity of the hormone. This natural mutation of the TSH-β subunit confirms the importance of the seat belt in the family of pituitary and placental glycoprotein hormones.
KW - central hypothyroidism
KW - gene mutation
KW - pituitary
KW - thyrotropin β subunit
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U2 - 10.1172/JCI118540
DO - 10.1172/JCI118540
M3 - Article
C2 - 8636437
AN - SCOPUS:13344295090
SN - 0021-9738
VL - 97
SP - 1250
EP - 1256
JO - Journal of Clinical Investigation
JF - Journal of Clinical Investigation
IS - 5
ER -