Transmembrane protein 109 is a protein that in humans is encoded by the TMEM109 gene. TMEM109 maps on chromosome 11, at 11q12.2, and is conserved in chimpanzee, dog, cow, mouse, and rat. The gene is also known as MGC5508, LOC79073. It has been described as transmembrane protein 109, mg23, mitsugumin-23. TMEM109 may mediate cellular response to DNA damage by protecting against ultraviolet C-induced cell death and can form voltage-gated calcium and potassium channels in vitro. TMEM109 is widely expressed in fat, lung, and other tissues. Diseases associated with TMEM109 include Spinal Cord Astrocytoma. 162 organisms have orthologs with the human gene TMEM109.