title: The structure of tissue on cell culture-extracted thyroglobulin is independent of its iodine content.
abstract: The major protein synthesized in vitro by the ovine thyroid cell line OVNIS 6H is the prothyroid hormone thyroglobulin. Purified from serum-free cell culture media using sucrose gradient centrifugation, the thyroglobulin dimer was analysed for iodine content and observed by electron microscopy. In their usual medium, the OVNIS 6H cells produce a very poorly iodinated thyroglobulin containing 0.05 I atom per molecule. When cultured with methimazole or propylthiouracil, two inhibitors of iodide organification, less than 0.007 I atom/molecules was found. These molecules purified from cell cultures were compared to those purified from ovine thyroid tissue containing 26 I atoms/mol. Despite large differences in iodine content, the three preparations all consist of 19 S thyroglobulin dimers with the classical ovoidal shape. The variability in size measurements remains in a 2% range for all thyroglobulin types. Consequently, no real significant variation can be found between the highly iodinated thyroglobulin isolated from tissue, and the poorly or non-iodinated thyroglobulins isolated from cells cultured with or without methimazole or propylthiouracil.
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D007455:Iodine; D046911:Macromolecular Substances; D008854:Microscopy, Electron; D011487:Protein Conformation; D012756:Sheep; D013329:Structure-Activity Relationship; D013954:Thyroglobulin
chemical_list: D046911:Macromolecular Substances; D013954:Thyroglobulin; D007455:Iodine