Transcription factor. Recognizes and binds to the consensus sequence motif 5-AATTAATTA-3 in the regulatory elements of target genes, such as glycoprotein hormones alpha chain CGA and visual system homeobox CHX10, positively modulating transcription, transcription can be co-activated by LDB2. Synergistically enhances transcription from the prolactin promoter in cooperation with POU1F1/Pit-1.