Acts as a transcriptional activator in complex with isoform 2 of meis1, to induce posterior neural and neural crest gene expression, and thereby specify hindbrain and neural crest cell fate. Binds to a highly conserved region in the promoter of the neural crest gene zic3. Required for the nuclear transport or retention of isoform 2 of meis1. Forms a heterodimer with isoform 2 of meis1; the interaction is necessary for neural fate induction. Shows broad, weak expression from blastula through gastrula stages. At stage 14/15, expressed in a broad arc that gives rise to the forebrain and eyes. More intensely expressed in the lateral neural folds (presumptive neural crest) and as horizontal stripes in the posterior neural plate that give rise to the hindbrain. As development proceeds, expression progresses posteriorly along the neural folds and at stage 21, expression is pronounced in the prospective hindbrain and in migratory neural crest cells. At later stages (stage 26), expression becomes intense within the dorsal portion of the forebrain, and in the optic cup, caudal branchial arch, peripheral to the pronephric anlage, and in the dorsal anterior half of the spinal cord. Expression remains robust in the hindbrain but gradually becomes more restricted. At stage 28, expressed in the dorsal lateral portion of the neural tube and in the somatic layer of the lateral plate mesoderm that surrounds the pronephric anlage. Expressed both maternally and zygotically. Expressed at a low level in unfertilized eggs with increased expression during late gastrula through neurula and tailbud stages. The displayed sequence corresponds to the ortholog of the mammalian isoform B sequences. There is currently no X.laevis ortholog sequence for isoform A. Belongs to the TALE/PBX homeobox family.