Transcription factor required for zygotic genome activation (ZGA), a critical event in early embryonic development during which the developmental control passes from maternally provided mRNAs to the expression of the zygotic genome after fertilization. Together with other Obox family members, required in early two-cell stage embryos to kick-start the major ZGA wave by facilitating RNA Polymerase II 'pre-configuration', during which RNA Polymerase II relocates from the initial one-cell stage binding targets to ZGA gene promoters and distal enhancers. Mechanistically, promotes recruitment of RNA Polymerase II from (CG-rich) non-ZGA genes to (CG-poor) ZGA genes at the two-cell stage. Binds to regulatory DNA sequences containing a 5'-ACNCCTTTAATCCCAG-3' sequence motif. Most maternal and zygotic Obox family proteins can compensate for one another. In addition to its role in ZGA, promotes embryonic stem cell pluripotency