Sequence-specific transcription factor that binds gene promoters and activates their transcription. May play a role in the development of anterior structures, and in particular, the brain and facies and in specifying the identity or structure of hindlimb. Acts as a transcriptional activator by binding to promoter sequences with a TAAT/GCC core motif. Expressed in primordial Rathke pouch, oral epithelium, first branchial arch, duodenum, and hindlimb. In the head region, first detected in 10-somite embryos in the stomodeum and rostral foregut. At day 3, expressed in Rathke pouch, in the mandibular and oral epithelia, in the foregut endoderm and in the posterior lateral plate mesoderm. Expression is maintained in these structures in later stages and at day 5, can be seen in the distal portion of the hindlimb. Belongs to the paired homeobox family. Bicoid subfamily.