Transcriptional repressor protein YY1（YY1）contains 4 C2H2-type zinc fingers and belongs to the YY transcription factor family. Multifunctional transcription factor exhibits positive and negative control on a large number of cellular and viral genes by binding to sites overlapping the transcription start site. The effect on transcription regulation of the protein is depending upon the context in which it binds and diverse mechanisms of action include direct activation or repression, indirect activation or repression via cofactor recruitment, or activation or repression by disruption of binding sites or conformational DNA changes. Its activity is regulated by transcription factors and cytoplasmic proteins that have been shown to abrogate or completely inhibit YY1-mediated activation or repression.