FANK1 was localized in the nuclei of the same cells within the seminiferous epithelium. Consistent with its nuclear localization, a gene ontology analysis suggests that FANK1 has a DNA binding activity and thus may function as a transcription factor. Given the highly restricted expression of FANK1, it may have a role in regulating gene expression in the transition from the meiotic phase to the haploid phase during spermatogenesis. Recombinant human FANK1 protein, fused to His-tag at N-terminus, was expressed in E.coli and purified by using conventional chromatography techniques.