Transcription factor that binds to the octamer motif (5'-ATTTGCAT-3'). Antagonizes the activity of nodal/activin signaling during gastrulation to suppress mesendoderm formation. Acts maternally to inhibit vegt and beta-catenin-activated gene transcription, probably by forming a transcriptional repression complex on the promoters of target genes. Binds to an octamer motif in interspersed RNA (By similarity). Interacts with the transcription factors tcf7l1/tcf3 and vegt. Belongs to the POU transcription factor family. Class-5 subfamily.