Thyroxine Binding Globulin (TBG) is a serpin produced in the liver with high affinity for the thyroid hormones T3 and T4. TBG reversibly binds T3 and T4, enabling their circulation around the bloodstream.
This protein is a preparation of human tenascin purified by precipitation, concentration and dialysis from tissue culture supernatant of the glioblastoma U-251 MG, formally distributed as U-373 MG, an astrocytoid adherent cell line, an over producer of human tenascin.
Horseradish Peroxidase (HRP) conjugated Protein A. Assay by Immunoelectrophoresis resulted in a single precipitin arc against anti-Peroxidase and anti-Protein A. No reaction was observed against anti-Protein G