DNA-binding protein that regulates the transcription of several genes and is involved in heart development and limb pattern formation. May bind to the core DNA motif of promoters. Monomer. Homodimer (via the T-box); binds DNA as homodimer. Shuttles between the cytoplasm and the nucleus. Early in the developing heart, uniformly expressed throughout the entire cardiac crescent. Upon formation of the linear heart tube, expressed in a graded fashion, stronger near the posterior end and weaker at the anterior end. As the heart tube loops, asymmetric expression continues; it is expressed in the presumptive left ventricle, but not the right ventricle or outflow tract. This pattern of expression is maintained in more mature hearts (PubMed:10373308). First detected in the presumptive wing and leg mesoderm respectively at around stages 14-15. As limb outgrowth proceeds, expressed throughout the mesoderm and in the wing (PubMed:9550719). The T-Box domain binds to double-stranded DNA.