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KMID : 0043320040270121275
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Archives of Pharmacal Research
2004 Volume.27 No. 12 p.1275 ~ p.1283
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Multimerization of Bovine Thyroglobulin, Partially Unfolded or Partially Unfolded/Reduced; Involvement of Protein Disulfide Isomerase and Glutathionylated Disulfide Linkage
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Liu Xi-Wen
Sok Dai-Eun
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Abstract
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Fate of the nascent thyrolglobulin (Tg) molecule is characterized by multimerization. To establish the formation of Tg multimers, the partially unfolded/reduced Tg or deoxycholate-treated/ reduced Tg was subjected to protein disulfide isomerase (PDI)-mediated multimerization. Oxidized glutathione/PDI-mediated formation of multimeric Tg forms, requiring at least an equivalent molar ratio of PDI/Tg monomer, decreased with increasing concentration of reduced glutathione (GSH), suggesting the oxidizing role of PDI. Additional support was obtained when PDI alone, at a PDI/Tg molar ratio of 0.3, expressed a rapid multimerization. Independently, the exposure of partially unfolded Tg to GSH resulted in Tg multimerization, enhanced by PDI, according to thiol-disulfide exchange. Though to a lower extent, a similar result was observed with the dimerization of deoxycholate-pretreated Tg monomer. Consequently, it is implied that intermolecular disulfide linkage may be facilitated at a limited region of unfolded Tg. In an attempt to examine the multimerization site, the cysteine residue-rich fragments of the Tg were subjected to GSH-induced multimerization; a 50 kDa fragment, containing three vicinal dithiols, was multimerized, while an N-terminal domain was not. Present results suggest that the oxidase as well as isomerase function of PDI may be involved in the multimerization of partially unfolded Tg or deoxycholate-treated Tg.
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KEYWORD
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Multimerization, Thyroglobulin (Tg), Partially unfolded reduced, Protein disulfide isomerase(PDI), Disulfide
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