Ten-Eleven Translocation Methylcytosine Dioxygenase 1 (TET1)

TET1, a fusion partner of the MLL gene in acute myeloid leukemia, is a 2-oxoglutarate (2OG)- and Fe(II)-dependent enzyme that catalyzes conversion of 5mC to 5-hydroxymethycytosine (hmC) in cultured cells and in vitro. hmC is present in the genome of mouse embryonic stem cells, and hmC levels decrease upon RNA interference-mediated depletion of TET1.LCX gene encodes a 2,136-amino acid protein with a zinc-binding CXXC domain (which MLL also contains) within a methyltransferase domain, 3 nuclear localizations signals, and an alpha-helical coiled-coil region. The MLL-LCX fusion protein lacked a CXXC domain of LCX, but retained an alpha-helical coiled-coil region at the C terminus, similar to MLL-AF6, MLL-AF1P, and other fusion proteins involved in the pathogenesis of 11q23-associated leukemia.