title: Role of multimerized porcine thyroglobulin in iodine storage.
abstract: Thyroglobulin (Tg), the prothyroid hormone, is stored in the lumen of the thyroid follicles as soluble dimers and tetramers and insoluble multimers, Soluble Tg is well characterized with regards to structure and role, but insoluble Tg (i-Tg) is not. Here we show that i-Tg, multimerized through formation of disulfide and dityrosine bonds, has a higher iodine content than soluble Tg and no thyroid hormones. Furthermore, the size and the resistance of i-Tg to proteolytic enzymes implied a new mechanism by which thyrocytes may degrade this form of Tg. Using peroxidase and H2O2 generating system, we found that about 80% of i-Tg was degraded and 24% of its iodine content was released. Our data point to a role for i-Tg in iodine storage and the involvement of TPO in i-Tg degradation and iodide release.
authors.affiliation: Faculté de Médecine, Unité 38 INSERM, Marseille, France.
authors.forename: N
authors.initials: N
authors.lastname: Baudry
authors.forename: P J
authors.initials: PJ
authors.lastname: Lejeune
authors.forename: F
authors.initials: F
authors.lastname: Delom
authors.forename: L
authors.initials: L
authors.lastname: Vinet
authors.forename: P
authors.initials: P
authors.lastname: Carayon
authors.forename: B
authors.initials: B
authors.lastname: Mallet
mesh_terms: D000596:Amino Acids / Q000032:analysis; D000818:Animals; D004105:Diiodotyrosine / Q000032:analysis; D004220:Disulfides / Q000737:chemistry; D004591:Electrophoresis, Polyacrylamide Gel; D006861:Hydrogen Peroxide / Q000378:metabolism; D007454:Iodides / Q000032:analysis; D007455:Iodine / Q000032:analysis / Q000378:metabolism*; D008855:Microscopy, Electron, Scanning; D007470:Monoiodotyrosine / Q000032:analysis; D009195:Peroxidase / Q000378:metabolism; D011402:Pronase / Q000378:metabolism; D011487:Protein Conformation; D013552:Swine; D013954:Thyroglobulin / Q000032:analysis / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D013961:Thyroid Gland / Q000737:chemistry / Q000201:enzymology / Q000378:metabolism; D013974:Thyroxine / Q000032:analysis; D014284:Triiodothyronine / Q000032:analysis; D014357:Trypsin / Q000378:metabolism; D014443:Tyrosine / Q000031:analogs & derivatives / Q000032:analysis
chemical_list: D000596:Amino Acids; D004220:Disulfides; D007454:Iodides; D014284:Triiodothyronine; D014443:Tyrosine; D004105:Diiodotyrosine; D013954:Thyroglobulin; D007455:Iodine; D006861:Hydrogen Peroxide; C007543:dityrosine; D009195:Peroxidase; D014357:Trypsin; D011402:Pronase; D007470:Monoiodotyrosine; D013974:Thyroxine