Transcription activator. Binds to the DNA sequence 5'-AACAAT-3'. All of the sox17 proteins are required for embryonic endoderm development and gastrulation movements, and show some redundancy in function. In addition, the sox17 proteins have distinct but overlapping roles in later gut development. Acts downstream of vegt-signaling in endoderm differentiation to induce a range of endodermal genes both directly (including endodermin and dhh/chh) and indirectly. Also represses wnt-responsive genes to inhibit wnt/beta-catenin signaling. Interacts (via C-terminus) with ctnnb1/beta-catenin (via Armadillo repeats); this interaction is required for inhibition of wnt-signaling. Enriched in the embryonic endoderm. Expressed in the embryonic gut, with strong expression in the posterior gut during tailbud stages. Expressed at a low level in the adult kidney and spleen. Involved in multiple regulatory feedback loops with other endodermal factors, including the nodal-related factors/Xnrs. Autoinduces. The 9aaTAD motif is a transactivation domain present in a large number of yeast and animal transcription factors.