KCTD4 has an N-terminal homodimerization domain that contains multiple copies of kelch repeats and/or C2H2-type zinc fingers. Proteins that contain BTB domains are thought to be involved in transcriptional regulation via control of chromatin structure and function. KCTD4 is a 259 amino acid protein that contains one BTB domain, suggesting a possible role as a transcriptional regulator. Recombinant human KCTD4 protein, fused to His-tag at N-terminus, was expressed in E.coli and purified by using conventional chromatography techniques.