Thyroglobulin, Human (Tg)

Thyroglobulin (TG) is the primary protein substrate in the formation of thyroid hormone. It accounts for the major portion of the thyroid gland mass. TG consists of a dimer of 2 identical proteins in a noncovalent linkage. Each monomer contains 2748 aa. TG has a MW of ~330kD, ~10% of the weight is due to glycosylation. The peptide chains may be found in monomeric and dimeric forms. TG is synthesized exclusively by the thyroid follicular cells. It is stored within the thyroid follicles where it comprises most of the thyroid colloid. The TG molecule contains ~110 tyrosine residues which form the substrate for thyroid hormone formation. Through an active transport mechanism, the thyroid gland traps iodide, which is oxidized to iodine within the thyroid follicles. Iodination of TG on tyrosine residues then occurs, resulting in the formation of mono- and di-iodotyrosine (MIT and DIT). MIT and DIT are then proteolytically cleaved from TG and are coupled to form the active thyroid hormones: triiodothyronine (MIT+DIT, T3) and thyroxine (DIT+DIT, T4). Both iodination and coupling are mediated by a peroxidase enzyme. The ratio of DIT to MIT in TG is ~2:1, while the final ratio of T4:T3 within the thyroid gland is ~3:1. T4 and T3 are then released into the bloodstream along with small amounts of TG. Thyroglobulin synthesis is stimulated at the transcriptional level by thyroid-stimulating hormone (TSH). Serum thyroglobulin levels are relatively high during late gestation and in cord blood. Levels decline during childhood and adolescence. Levels are slightly higher in term newborn females as compared to males.\n\nApplications:\nSuitable for use as a standard in immunoassays for determination of serum thyroglobulin levels, immunogen for antisera production, tracer for iodination.\n\nRecommended Dilutions:\nOptimal dilutions to be determined by the researcher. \n\nStorage and Stability: Lyophilized powder may be stored at -20 degrees C. Stable for 12 months at -20 degrees C. Reconstitute with sterile dH2O. Aliquot to avoid repeated freezing and thawing. Store at -20 degrees C. For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap. Further dilutions can be made in assay buffer.

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