Thyroid-stimulating hormone (TSH or thyrotropin), produced in human pituitary glands, has a molecular mass of 25kD. An Important indicator of thyroid function, TSH is used to monitor thyroid associated diseases. Thyroid-stimulating hormone is a hormone synthesized and secreted by thyrotrope cells in the anterior pituitary gland which regulates the endocrine function of the thyroid gland. TSH stimulates the thyroid gland to secrete the hormones thyroxine (T4) and triiodothyronine (T3). TSH production is controlled by a Thyrotropin Releasing Hormone (TRH), which is manufactured in the hypothalamus and transported to the anterior pituitary gland, where it increases TSH production and release. Somatostatin is also produced by the hypothalamus, and has an opposite effect on the pituitary production of TSH, decreasing or inhibiting its release.
The level of Thyroid hormones (T3 and T4) in the blood have an additional effect on the pituitary release of TSH. When the levels of T3 and T4 are low, the production of TSH is increased, and conversely, when levels of T3 and T4 are high, then TSH production is decreased. This effect creates a regulatory negative feedback loop. TSH is a glycoprotein and consists of two subunits, the alpha and the beta subunit. The alpha subunit is identical to that of human chorionic gonadotropin (HCG), luteinizing hormone (LH), follicle-stimulating hormone (FSH). The beta subunit is unique to TSH, and therefore determines its function.
TSH is a member of the cystine knot growth factor superfamily. It is a heterodimer of a 15kD unique subunit, TSH beta, with a 14kD alpha subunit, CGa (common glycoprotein hormone alpha) that is shared with lutropin (LH), follitropin (FSH) and chorionic gonadotropin (CG). Beta subunits of the four glycoprotein hormones share a 37-43% amino acid identity. Mature human TSH beta shares a 92%, 90%, 90%, 89%, 89%, 89%, and 88% aa identity with dog, rat, horse, mouse, cow, pig, and cat TSH b, respectively. Mature human CGa shares a 69%-73% aa identity with dog, rabbit, rat, mouse, cow, sheep, pig, cat and horse CGa. Each subunit forms a cystine knot structure with three disulfide bridges. A loop of the TSH beta subunit, termed a 'seat-belt', wraps around the CGa subunit to stabilize non-covalent association of the subunits, and also confers receptor selectivity.
Structure and charge of the three N-linked carbohydrate chains influence activity; the most complex forms have lower activity but longer halflife. Bovine and porcine TSH bind human TSH receptors (TSHR) with high affinity. The hypothalamic peptide TRH stimulates production and secretion of TSH by thyrotrophs (basophile cells) in the anterior pituitary gland. TSH travels to thyroid TSHR to stimulate production of thyroxine (T4). In the tissues, T4 is converted to the active form of thyroid hormone, triiodothyronine (T3), which completes a feedback loop by inhibiting TSH production. Studies in mouse identify bone marrow as a secondary site of TSH production. In bone, TSH signaling through TSHR on osteoblast and osteoclast precursors negatively regulates skeletal remodeling. Bone marrow cells that produce TSH may also circulate to the thyroid and appear to modulate thyroid hormone activity in times of immunological stress.
DNA sequences encoding human TSH-a (residues 1-116; Accession # P01215) and human TSH-b (residues 1-138; Accession # P01222) were co-expressed in Chinese Hamster Ovary cells.
Calculated molecular masses of 10.2 and 13.5kD, respectively. The recombinant protein is a non-covalent linked heterodimer. As a result of glycosylation, the recombinant human TSH a/b migrates at approximately 15-29kD on SDS-PAGE under reducing conditions.
Activity:Measured by its ability to induce cAMP accumulation in human TSH receptor transfected HEK293 cells. transfected HEK293 cells. ED50 0.25-1.5ng/ml
Storage and Stability:Lyophilized and reconstituted products are stable for 6 months after receipt at -20°C. Reconstitute with sterile PBS. Aliquot to avoid repeated freezing and thawing. Store at -20°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.
仕様
Size：10ug
Source Antigen：Recombinant, CHO cells
Grade：Purified
Purity：≥90%, as determined by SDS-PAGE under reducing conditions and visualized by silver stain. Endotoxin: ≤1EU/1ug (LAL)
Form：Supplied as a lyophilized powder in PBS, pH 7.4, containing 0.05mg/ug BSA. Reconstitute with 100ul sterile PBS
