Acts partially redundantly with other irx members in neural patterning. Required for formation of the posterior forebrain, midbrain, hindbrain, and to a lesser extent, spinal cord. Acts early in neural plate development to induce expression of some but not all proneural genes, and specify a neural precursor state. Also up-regulates repressors that prevent neuronal differentiation. Patterns the neuroectoderm in both the anterior/posterior and dorsal/ventral axes. Acts primarily as a transcriptional repressor during neural development, and binds to the bmp4 promoter to repress gene expression and thus mediate down-regulation of bmp4 by wnt signaling. Controls multiple processes through bmp4-repression including neural plate development, neural crest specification and Spemann organizer development. Involved in the specification of the preplacodal field at the anterior border of the neural plate. Regulates the genetic cascade of interactions that are necessary for positioning the isthmus organizer and the formation of the midbrain-hindbrain boundary. Required during at least two stages of pronephros kidney development; during neurula stages, maintains transcription of key renal genes to define the size and identity of the pronephric anlage, probably in part through regulation of bmp-signaling. Subsequently required for proper formation of the intermediate tubule segment of the pronephros. Acts principally as a transcriptional activator during pronephros development (By similarity). Belongs to the TALE/IRO homeobox family.