Inactivation of the jerky gene by insertion of a transgene into the mouse genome results in epileptic seizures in transgenic mice. This finding indicates that the jerky gene plays an important role in inducing epilepsy syndromes in mice. We report here our efforts in cloning, chromosomal mapping, and analysis of tissue distribution of a novel human gene, the HHMJG, a homologue to the mouse jerky gene product. We have successfully identified a full length cDNA clone encoding a novel human protein homologous to the mouse jerky gene product. The finding was based on the result of an analysis of EST (expressed sequence tag) sequences of a clone from a human tonsil cDNA library. A 4.0 kb mRNA species of the HHMJG is abundantly expressed in the majority of human tissues examined, including brain and skeletal muscle. However, in the testes, two mRNA species of the HHMJG, approximately 2.0 and 4.0 kb, are abundantly expressed. Sequence analysis of the HHMJG cDNA indicates that it encodes a putative protein of 51 kD, which shares significant sequence homology to not only the mouse jerky gene product but also some nuclear regulatory proteins, such as centromere binding protein-B. The predicted nuclear localization of the HHMJG product suggests that this protein may function as a nuclear regulatory protein. The result of human chromosomal mapping shows that the HHMJG is located on human chromosome 11q21. Our identification of the HHMJG cDNA provides a potential gene candidate to further investigate the biological significance and clinical implications of the HHMJG in human epilepsy.