TPO Human, Biotin

Human recombinant TPO, particularly the biotinylated form, is produced using recombinant DNA technology. This involves the expression of the TPO gene in suitable host cells, such as Sf9 insect cells . The biotinylation of TPO allows for easy detection and purification using streptavidin-based methods. The recombinant TPO is typically a glycosylated polypeptide chain containing 834 amino acids and has a molecular mass of approximately 93 kDa (excluding glycosylation) .

TPO is an integral membrane protein located on the apical membrane of thyroid follicular cells. It is essential for the biosynthesis of thyroid hormones, which are critical for regulating metabolism, growth, and development . The enzyme catalyzes two key reactions:

1. Iodination of Tyrosyl Residues: TPO facilitates the addition of iodine to tyrosine residues in thyroglobulin.
2. Coupling of Iodotyrosyl Residues: TPO catalyzes the coupling of iodotyrosyl residues to form the precursors of T4 and T3 .

TPO is also known to be an autoantigen in autoimmune thyroid diseases, such as Hashimoto’s thyroiditis and Graves’ disease. Autoantibodies against TPO can interfere with its function, leading to thyroid dysfunction .

Biotinylated human recombinant TPO is widely used in research and diagnostic applications. It is utilized in enzyme-linked immunosorbent assays (ELISA) to detect and quantify TPO antibodies in serum, which is important for diagnosing autoimmune thyroid diseases .

Recombinant TPO should be stored at 4°C if used within 2-4 weeks or frozen at -20°C for longer periods. It is important to avoid multiple freeze-thaw cycles to maintain its stability and activity .