Involved in the transcriptional regulation of genes required for muscle differentiation. Binds to a palindromic site (called T site) and activates gene transcription when bound to such a site (By similarity). Monomer. Differentiating muscle and tailbud tip. First detected in the vegetal hemisphere at the 32-cell stage. Expression continues in endothelial lineage until 110-cell stage when it declines here and becomes evident in muscle lineage cells. Expression increases throughout gastrulation and neurulation in differentiating muscle cells until late tailbud stage. Expression also detected in the tailbud tip from mid-gastrulation to tail elongation.