Enables DNA-binding transcription factor activity and sequence-specific DNA binding activity. Involved in atrioventricular canal development; heart looping; and regulation of heart contraction. Acts upstream of or within heart valve development and positive regulation of DNA-templated transcription. Predicted to be active in nucleus. Is expressed in several structures, including forebrain neural keel; nervous system; optic vesicle; pericardial region; and presumptive neural retina. Orthologous to human FOXN4 (forkhead box N4).