The four human glycoprotein hormones chorionic gonadotropin (CG), luteinizing hormone (LH), follicle stimulating hormone (FSH), and thyroid stimulating hormone (TSH) are dimmers consisting of alpha and beta subunits that are associated noncovalently. The alpha subunits of these hormones are identical, however, their beta chains are unique and confer biological specificity. Thyroid stimulating hormone functions in the control of thyroid structure and metabolism. TSHB is the beta subunit of thyroid stimulating hormone. Mutations in this gene result in congenital hypothyroidism. Recombinant human TSHB protein, fused to His-tag at N-terminus, was expressed in E.coli