Transcription factor with sequence-specific DNA binding activity. Binds to the consensus sequence 5'-[AT][AT]CAA[AT]G-3', showing a preference for 5'-AACAAT-3' and 5'-AACAAAG-3'. Inhibits beta-catenin-mediated dorsal axis specification by binding to sites within the promoter of the beta-catenin-regulated gene nodal5. Acts maternally as a transcriptional repressor of nodal5 and nodal6 to restrict their expression to the vegetal hemisphere of early embryos and thus establish germ layer formation. Acts at multiple points to inhibit nodal signaling, repressing the expression of the other mesoderm-inducing nodal genes nodal, nodal2 and nodal4, and also acting downstream to induce expression of genes including trim33/ectodermin, ema and coco, whose products repress nodal signaling 