Homeobox protein TGIF1

Homeobox protein TGIF1 is a is_associated_with::protein that in humans is encoded by the TGIF1 is_associated_with::gene. Alternative splicing has been observed at this locus and eight variants, encoding four distinct isoforms, are described.

Function
The protein encoded by this gene is a member of the three-amino acid loop extension (TALE) superclass of atypical homeodomains. TALE is_associated_with::homeobox proteins are highly conserved transcription regulators. This particular homeodomain binds to a previously characterized is_associated_with::retinoid X receptor responsive element from the cellular retinol-binding protein II promoter. In addition to its role in inhibiting 9-cis-retinoic acid-dependent RXR alpha transcription activation of the retinoic acid responsive element, the protein is an active transcriptional co-repressor of SMAD2 and may participate in the transmission of nuclear signals during development and in the adult.

Clinical significance
Mutations in this gene are associated with is_associated_with::holoprosencephaly type 4, which is a structural anomaly of the brain.

Interactions
Homeobox protein TGIF1 has been shown to interact with:
 * is_associated_with::C-jun,
 * is_associated_with::CTBP1,
 * is_associated_with::HDAC1,  and
 * is_associated_with::Mothers against decapentaplegic homolog 2.