Probably plays a role in the development of the brain and the sense organs. Can bind to the BCD target sequence (BTS): 5'-TCTAATCCC-3' (By similarity). May play a role in the specification or differentiation of neurons in the deep layers of the cerebral cortex, and also in cerebellar regionalization during early development. Brain: restricted regions of the developing rostral brain including the presumptive cerebral cortex and olfactory bulbs; expressed in the developing olfactory, auricolar and ocular systems, including the covering of the optic nerve. Expressed throughout the forebrain and midbrain during development, and in addition is also seen in discrete spatial and temporal domains in the developing cerebral cortex and cerebellum. Confined to a subpopulation of neurons in layers 5 and 6 within the adult cerebral cortex and during development expression is high in the progenitors of these deep-layer cells. Expressed in the developing cerebellum in spatially restricted regions of the external granular layer. Belongs to the paired homeobox family. Bicoid subfamily.