Methylcytosine dioxygenase TET1 (Tet1)

Dioxygenase that catalyzes the conversion of this modified genomic base 5-methylcytosine (5mC) into 5- hydroxymethylcytosine (5hmC) and plays an integral role in active DNA demethylation. Also mediates following conversion of 5hmC into 5- formylcytosine (5fC), and conversion of 5fC to 5-carboxylcytosine (5caC).

Conversion of 5mC to 5hmC, 5fC and 5caC probably constitutes the initial step in cytosine demethylation. Methylation in the C5 position of cytosine bases is an epigenetic modification of the mammalian genome that has a significant role in transcriptional regulation.