JMJD1A (Jumonji domain containing 1A), also known as TSGA (testis-specific protein A), JMJD1, KDM3A, JHDM2A (JMJC domain-containing histone demethylation protein 2A) or JHMD2A, is a member of the JHDM2 histone demethylase family of proteins that is predominantly expressed in testis. Containing one JMJC domain and a C-terminal C2HC4 zinc finger, JMJD1A functions as a mono- and dimethylation-specific demethylase, binding iron and a-ketoglutarate as cofactors and demethylating Lysine 9 of Histone H3. This suggests that JMJD1A plays a central role in the histone code and participates in nuclear hormone receptor-based transcriptional regulation. In addition, JMJD1A plays an important role in the regulation of cell growth during development and in chromatin regulation. JMJD1A directly regulates the expression of TNP1 and Protamine 1 (proteins required for the proper packaging and condensation of sperm chromatin) and, therefore, plays an essential role in spermatogenesis.
