title: Photoaffinity labelling of the TSH receptor on FRTL5 cells.
abstract: An investigation of the properties of TSH receptors on FRTL5 cells using affinity labelling with a 125I-labelled photoactive derivative of TSH is described. Our studies suggest that FRTL5 cells contain 2 principal types of cell surface TSH receptors. One form, probably a precursor, consists of a single polypeptide chain (Mr 120,000) with an intrachain loop of amino acids formed by a disulphide bridge. The other type of receptor consists of a water-soluble A chain (Mr 55,000) linked to an amphiphilic B chain (Mr 35,000) by a disulphide bridge. The 2 chain structure is probably derived from the single chain 120,000 protein by enzymatic cleavage of peptide sequences within the loop of amino acids formed by the intrachain disulphide bridge.
mesh_terms: D000345:Affinity Labels; D000818:Animals; D001345:Autoradiography; D002460:Cell Line; D004229:Dithiothreitol; D004591:Electrophoresis, Polyacrylamide Gel; D010777:Photochemistry; D051381:Rats; D011989:Receptors, Thyrotropin / Q000378:metabolism*; D012995:Solubility; D013961:Thyroid Gland / Q000378:metabolism*
chemical_list: D000345:Affinity Labels; D011989:Receptors, Thyrotropin; D004229:Dithiothreitol