HMGN3, also known as high mobility group nucleosomal binding domain 3, binds thyroid hormone receptor beta, but only in the presence of thyroid hormone. Thyroid hormone receptors are hormone-dependent transcription factors that regulate expression of a variety of specific target genes. It is thought to reduce the compactness of the chromatin fiber in nucleosomes, thereby enhancing transcription from chromatin templates. Recombinant human HMGN3 protein, fused to His-tag at N-terminus, was expressed in E.coli and purified by using conventional chromatography.