An EVH1/WH1 domain as a key actor in TGFbeta signalling.

EVH1 (enabled VASP (vasodilator-stimulated protein) homology 1)/WH1 (WASP (Wiskott-Aldrich syndrome protein) homology 1) domains, present in Ena VASP and WASP, are protein interaction modules specialised in binding proline-rich ligands. An EVH1/WH1 domain is here identified in the recently cloned SMIF protein, a key protein in transforming growth factor-beta (TGFbeta) signalling which was not yet related to defined domains. The SMIF EVH1/WH1 domain interacts with the proline-rich Smad4 activation domain, leading to translocation of so-formed complex to the nucleus where SMIF possesses strong intrinsic TGFbeta-inducible transcriptional activity. This finding highlights the pivotal role that the EVH1/WH1 family of domains play in multiple eukaryotic signal transduction pathways.