Paired box protein Pax-8 isoform PAX8E, also known as PAX8, is expressed in the developing and adult thyroid, the developing secretory system and at lower levels, in the adult kidney. PAX8complexes with TTF-1 and TTF-2 to induce thyroid follicular cell differentiation and thyroid hormone biosynthesis by regulating the expression of sodium iodide symporter (NIS), thyroid peroxidase (TPO), thyroglobulin (TG) and the thyrotropin receptor (TSHR). Defects in PAX8 are the cause of congenital hypothyroidism non-goitrous type 2 (CHNG2). Recombinant human PAX8 protein, fused to His-tag at N-terminus, was expressed in E.coli and purified by using conventional chromatography techniques.