In addition to esBAF, the TIP60-p400 complex is also required for maintaining the self-renewal potential and pluripotency of ESCs87. Using promoter microarrays, p400 was found at more than one-half of all promoters across the genome in mouse ESCs, and the intensity of binding was similarly correlated with the activity of the gene. The complex seems to be recruited to its targets in two ways, directly by the H3K4me3 mark and indirectly by Nanog. Although the TIP60-p400 complex has histone-acetyltransferase activity, which is generally associated with gene activation, this complex functions mainly to repress developmental genes. Hence, TIP60-p400 might deposit H4 acetylation marks that function in an unconventional manner to mediate gene repression.
