Transcription factor that is selectively and transiently expressed in cleavage-stage embryos. Binds to double-stranded DNA elements with the consensus sequence 5'- TAATCTAATCA-3'. Binds to chromatin containing histone H3 acetylated at 'Lys-27' (H3K27ac) and promotes deacetylation of H3K27ac. In parallel, binds to chromatin that lacks histone H3 acetylation at 'Lys-27' (H3K27ac) and recruits EP300 and CREBBP to promote acetylation of histone H3 at 'Lys-27' at new sites. Involved in transcriptional regulation of numerous genes, primarily as transcriptional activator, but mediates also repression of a set of target genes. Promotes expression of ZSCAN4 and KDM4E, two proteins with essential roles during early embryogenesis. Heterologous expression in cultured embryonic stem cells mediates also transcription of HERVL retrotransposons and transcripts derived from ACRO1 and HSATII satellite repeats. May activate expression of PITX1. May regulate microRNA (miRNA) expression. Inappropriate expression can inhibit myogenesis and promote apoptosis. Probably inactive as a transcriptional activator, due to the absence of the C-terminal region that is important for transcriptional activation. Can inhibit transcriptional activation mediated by isoform 1. Heterologous expression of isoform 2 has no deleterious effect on cell survival.