Transcription factor that forms a trimeric complex with OCT4 on DNA and controls the expression of a number of genes involved in embryonic development such as YES1, FGF4, UTF1 and ZFP206 (By similarity). Binds to the proximal enhancer region of NANOG (By similarity). Critical for early embryogenesis and for embryonic stem cell pluripotency (By similarity). Downstream SRRT target that mediates the promotion of neural stem cell self-renewal (By similarity). Keeps neural cells undifferentiated by counteracting the activity of proneural proteins and suppresses neuronal differentiation (By similarity). May function as a switch in neuronal development (By similarity). Interacts with ZSCAN10 (By similarity). Interacts with SOX3 and FGFR1 (By similarity). Interacts with GLIS1 (By similarity). Interacts with POU5F1; binds synergistically with POU5F1 to DNA (By similarity). The 9aaTAD motif is a transactivation domain present in a large number of yeast and animal transcription factors. Sumoylation inhibits DNA binding and negatively regulates the FGF4 transactivation.