Formins include several families of proteins that regulate actin cytoskeletal dynamics via two conserved formin homology domains, FH1 and FH2. The FH1 region contains poly-proline stretches that promote interactions with profilin. The FH2 domain, located C-terminally to the FH1 domain, is highly conserved in formin proteins and possesses actin nucleation and polymerization activities. Through cooperation of FH1 and FH2, formins construct actin-based structures comprising linear, unbranched filaments that are used in stress fibers, actin cables, microspikes, and contractile rings. Dishevelled associated activator of morphogenesis proteins (DAAM1 and DAAM2) are formin family members involved in WNT signaling. DAAM1 is ubiquitously expressed and may be important for regulating actin dynamics in several cell types. DAAM1 can bind RhoGTPase and dishevelled in WNT signaling pathways, and interacts with the SH3 domains of cell signaling mediators, such as c-Src.
