RABBIT ANTIBODIES AGAINST 2 DIFFERENT EXTRACELLULAR DOMAINS OF HUMAN THYROTROPIN RECEPTOR POSSESS THYROID STIMULATING ACTIVITIES

We have produced rabbit antibodies against synthetic peptides corresponding to the mid-region (amino acid residues 172-202, C peptide) and to the unique segment near the transmembrane region (amino acid residues 341-370, P peptide) in the extracellular component of the human thyrotropin (TSH) receptor and evaluated their biological activities. Both anti-C peptide antibodies raised in two rabbits showed strong thyroid stimulating activities (TSAb) (4127 % and 2548 %). Anti-P peptide antibodies raised in two rabbits were also strongly positive for TSAb activities (359 % and 3468 %). However, none of these antibodies had TSH-binding inhibitor immunoglobulin (TBII) activities. These results suggest that the domains responsible for TSAb are likely to span the entire extracellular component of the TSH receptor. © 1991.