Open AccessTwo-subunit structure of the human thyrotropin receptor.
Author(s) -
H Loosfelt,
Chantal Pichon,
André Jolivet,
Micheline Misrahi,
Bernard Caillou,
M Jamous,
Brigitte Vannier,
Edwin Milgröm
Publication year - 1992
Publication title -
proceedings of the national academy of sciences
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.89.9.3765
Subject(s) - protein subunit , thyrotropin receptor , extracellular , biochemistry , g alpha subunit , molecular mass , receptor , microbiology and biotechnology , biology , intracellular , interleukin 10 receptor, alpha subunit , chemistry , thyroid , enzyme , endocrinology , gene , graves' disease
The extracellular and intracellular domains of the human thyrotropin receptor were expressed in Escherichia coli and the proteins were used to produce monoclonal anti-receptor antibodies. Immunoblot studies and immunoaffinity purification showed that the receptor is composed of two subunits linked by disulfide bridges and probably derived by proteolytic cleavage of a single 90-kDa precursor. The extracellular alpha subunit (hormone binding) had an apparent molecular mass of 53 kDa (35 kDa after deglycosylation with N-glycosidase F). The membrane-spanning beta subunit seemed heterogeneous and had an apparent molecular mass of 33-42 kDa. Human thyroid membranes contained a 2.5- to 3-fold excess of beta subunits over alpha subunits. Immunocytochemistry showed the presence of both subunits in all the follicular thyroid cells, and both subunits were restricted to the basolateral region of the cell membrane.
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