TET4

TET4 refers to a potential fourth member or homolog of the TET (Ten-Eleven Translocation) family of dioxygenases that are involved in DNA demethylation through oxidation of 5-methylcytosine. In humans, the TET family is typically described as TET1, TET2, and TET3, which catalyze iterative oxidation steps and play roles in epigenetic regulation and development. TET4 is not established as a canonical human gene; in many vertebrate genomes, a TET4-like open reading frame has been predicted, but its status as a bona fide functional enzyme remains uncertain.

Nomenclature and availability: In genomic and transcript databases some entries label a TET4 gene or transcript; many are predicted models with sparse experimental support. Because of this, some researchers treat TET4 as a placeholder for putative TET-like proteins until validated by expression, enzymatic assays, and genetic studies.

Function and evidence: There is limited direct evidence for a conserved catalytic activity of a TET4 protein in vertebrates. No widely accepted knockout or loss-of-function phenotypes for TET4 have been reported, and the extent to which a TET4 homolog contributes to DNA demethylation, 5-hydroxymethylcytosine formation, or epigenetic regulation remains unclear.

Evolution and context: The expansion of the TET family varies by lineage; some non-mammalian species may harbor additional TET-like genes or paralogs. The identification of a conserved TET4 across species is an area of ongoing investigation, with some annotations later revised as partial or nonfunctional fragments.

See also: TET1, TET2, TET3.