Extracellular domain chimeras of the TSH and LH/CG receptors reveal the mid-region (amino acids 171-260) to play a vital role in high affinity TSH binding.
We constructed a series of TSH-LH/CG receptor chimeras by homologous substitution of relatively small regions of the TSH receptor extracellular domain for the corresponding region of the extracellular domain of the LH/CG receptor. Constructs were stably expressed in Chinese hamster ovary cells. Of the five chimeric receptors, only TSH-LHR-14, which contains mid-region domain C (amino acid residues 171-260) of the extracellular component of the TSH receptor, exhibited TSH binding of relatively high affinity. Consistent with this TSH binding, chimera TSH-LHR-14 was the only one that demonstrated a functional response to TSH stimulation in terms of intracellular cAMP generation. These data indicate that domain C plays a vital role in TSH receptor function.
Nagayama
Y
Y
Thyroid Molecular Biology Unit, V.A. Medical Center, San Francisco, California 94121.
Russo
D
D
Chazenbalk
G D
GD
Wadsworth
H L
HL
Rapoport
B
B
D000595:Amino Acid Sequence; D000818:Animals; D001667:Binding, Competitive; D002460:Cell Line; D006224:Cricetinae; D003412:Cricetulus; D000242:Cyclic AMP / Q000378:metabolism; D006801:Humans; D008024:Ligands; D051381:Rats; D011967:Receptors, Gonadotropin / Q000187:drug effects / Q000378:metabolism*; D011974:Receptors, LH / Q000187:drug effects / Q000378:metabolism*; D011989:Receptors, Thyrotropin / Q000187:drug effects / Q000378:metabolism*; D011994:Recombinant Proteins
D008024:Ligands; D011967:Receptors, Gonadotropin; D011974:Receptors, LH; D011989:Receptors, Thyrotropin; D011994:Recombinant Proteins; D000242:Cyclic AMP