Thyroxine Binding Globulin (TBG) (SERPINA7) Antibody – Mouse Monoclonal

There are three proteins including thyroxine-binding globulin (TBG), transthyretin and albumin responsible for carrying the thyroid hormones thyroxine (T4) and 3,5,3 -triiodothyronine (T3) in the bloodstream. This gene encodes the major thyroid hormone transport protein, TBG, in serum. It belongs to the serpin family in genomics, but the protein has no inhibitory function like many other members of the serpin family. Mutations in this gene result in TGB deficiency, which has been classified as partial deficiency, complete deficiency, and excess, based on the level of serum TBG. Alternatively spliced transcript variants encoding different isoforms have been found, but the full-length nature of these variants has not been determined.

Function: Major thyroid hormone transport protein in serum.

Subcellular location: Secreted.

Tissue specificity: Expressed by the liver and secreted in plasma.

Polymorphism: Two qualitative TBG variants occur in particular populations. TBG-A is found in 40% of Australian aborigines, it has reduced affinity for thyroxine and triiodothyroxine and increased susceptibility to inactivation by heat or acid. TBG-S ('s' for slow shift on isoelectic focusing) is found in blacks, Eskimos, Melanesians, Polynesians and Indonesians, but not in Caucasians; TBG-S is slightly more thermolabile.

Involvement in disease: Defects in SERPINA7 are a cause of thyroxine-binding globulin deficiency (TBG deficiency) [

MIM:314200]. Mutations in the SERPINA7 gene can result as a whole spectrum of deficiencies, characterized by either reduced or increased TBG levels in the serum. Patients show, respectively, reduced or elevated protein-bound iodine but are euthyroid.

Sequence similarities: Belongs to the serpin family.