GABPA (GA binding protein transcription factor alpha subunit) is one of three GA-binding protein transcription factor subunits which functions as a DNA-binding subunit. Since this subunit shares identity with a subunit encoding the nuclear respiratory factor 2 gene, it is likely involved in activation of cytochrome oxidase expression and nuclear control of mitochondrial function. This subunit also shares identity with a subunit constituting the transcription factor E4TF1, responsible for expression of the adenovirus E4 gene. Because of its chromosomal localization and ability to form heterodimers with other polypeptides, it may play a role in the Down Syndrome phenotype.