Stable expression of the human TSH receptor in CHO cells and characterization of differentially expressing clones

The human thyrotropin receptor cDNA was transfected in CHO cells and individual clones were isolated. They were tested for their response to thyrotropin, forskolin and antibodies from a patient with high levels of thyroid stimulating antibodies. Several clones were characterized extensively with respect to membrane binding of labeled thyrotropin, cAMP accumulation in response to thyrotropin and kinetics of cAMP production. Data for three representative clones are presented. Receptor number as assessed by membrane binding of labeled thyrotropin, and cAMP production, measured in a thyrotropin response bioassay, are correlated. The Kd value for the human thyrotropin receptor expressed in CHO was estimated to be 50 pM.