E4 promoter-binding protein 4 (E4BP4) functions as a transcriptional regulator that recognizes and binds to the sequence 5'-[GA]TTA[CT]GTAA[CT]-3', a sequence present in many cellular and viral promoters. E4BP4 activates transcription from the interleukin-3 promoter in T-cells and is a component of the circadian clock that acts as a negative regulator for the circadian expression of PER2 oscillation in the cell-autonomous core clock [taken from the Universal Protein Resource (UniProt) www.uniprot.org/uniprot/Q16649].