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. Can independently activate and synergize with PIT-1 on pituitary-specific target gene promoters, thus may subserve functions in generating both precursor and specific cell phenotypes in the anterior pituitary gland and in several other organs. Can activate pituitary transcription of the proopiomelanocortin gene. Interacts with POU1F1. Expressed in primordial Rathke pouch, oral epithelium, first branchial arch, duodenum, and hindlimb. Expressed throughout pituitary development. Not found in 8 dpc embryos but seen in embryos at 8.5 dpc in the region of the first branchial arch and ventral portion of the caudal-most region of the embryo. At 9.5 dpc observed in the hindlimb buds, maxillary and mandibular components of the first branchial arch and Rathke pouch and the pattern of expression continues through 10.5 dpc at 11.5 dpc also found in ventral mesenchyme covering the abdominal cavity and in the nasal epithelium. At 17.5 dpc expressed in derivatives of the first branchial arch, including tongue and mandible as well as duodenum, salivary glands, nasal epithelium and condensing cartilage in the hindlimbs. Belongs to the paired homeobox family. Bicoid subfamily.