The Thioredoxin Boxes of Thyroglobulin: Possible Implications for Intermolecular Disulfide Bond Formation in the Follicle Lumen
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Markus Klein
Abstract
Multimerization of thyroglobulin (TG) takes place extracellularly in the thyroid follicle lumen and is regarded as a mechanism to store TG at high concentrations. Human thyroglobulin (hTG) has been shown to multimerize mainly by intermolecular disulfide crosslinks. We recently noted that TG of various mammalian species contains three highly conserved thioredoxin boxes (CXXC). This sequence is known to underlie the enzymatic activity of protein disulfide isomerase (PDI). As hTG formed intermolecular disulfide bonds in the absence of other proteins depending on the redox conditions and hTG concentration, the CXXCboxes of TG might provide the structural basis for selfassisted intermolecular crosslinking. To test this hypothesis we prepared a recombinant TG fragment containing the three thioredoxin boxes. This fragment exhibited a redox activity amounting to about 10 % of the activity of PDI at redox conditions supposed to be present in the extracellular space. This activity might be supplemented by the oxidizing system of the apical cell surfaces of thyrocytes facing the follicle lumen. Indeed, incubation of hTG with peroxidase and H[2]O[2] resulted in intermolecular disulfide bridge formation. Our results suggest a combined mechanism of selfassisted and peroxidasemediated disulfide bond formation leading to the intermolecular crosslinking of lumenal hTG.
Copyright © 2000 by Walter de Gruyter GmbH & Co. KG
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Articles in the same Issue
- Characterization of Regulatory Elements in the 5'-Flanking Region of the GM2 Activator Gene
- Transcriptional Activity of GLI1 Is Negatively Regulated by Protein Kinase A
- Peptide Bond Synthesis: Function of the efp Gene Product
- Molecular Cloning, Expression and Purification of Muscle Fructose-1,6-Bisphosphatase from Zaocys dhumnades: the Role of the N-Terminal Sequence in AMP Activation at Alkaline pH
- The pH-Dependent Interaction of Cinnamomin with Lipid Membranes Investigated by Fluorescence Methods
- Nitric Oxide Detection and Visualization in Biological Systems. Applications of the FNOCT Method
- Processing of V-ATPase Subunit B of Mesembryanthemum crystallinum L. Is Mediated in Vitro by a Protease and/or Reactive Oxygen Species
- The Thioredoxin Boxes of Thyroglobulin: Possible Implications for Intermolecular Disulfide Bond Formation in the Follicle Lumen
- New Bivalent Thrombin Inhibitors with N? (Methyl)Arginine at the P1-Position
- Multiple Promoters Direct the Tissue-Specific Expression of Rat Mitochondrial Glycerol-3-Phosphate Dehydrogenase
- Characterization of SNP, a Novel Tissue- and Phase-Specific Nuclear Protein Expressed during the Proliferative Phase in the Oviduct of the Lizard Podarcis sicula Raf.
- Association of Betaine-Homocysteine S-Methyltransferase with Microtubules
- Re-Evaluation of Amino Acid Sequence and Structural Consensus Rules for Cysteine-Nitric Oxide Reactivity
- Expression of Human Tissue Kallikrein in Differentiated HL-60 Cells
- Erratum
