The FH1 domain of DAAM1 recruits Profilin1 (PFN1) to the DVL:DAAM1 complex, and DAAM1 and PFN1 colocalize at stress fibers in response to WNT signaling (Sato et al, 2006). In addition to binding to FH domains, Profilin proteins bind to monomeric actin and in this way serve as a source of actin for polymerization of unbranched actin chains (Birbach, 2008; Goode and Eck, 2007). Depletion of PFN1 inhibits stress fiber formation in response to WNT signaling but does not affect DAAM1-mediated RHO A activation. In vivo, PFN1 is required downstream of DAAM1 for blastopore closure in Xenopus (Sato et al, 2006). In another study, PFN2 was also identified as an FH1 domain-interacting partner of DAAM1. The roles of PFN1 and PFN2 appear to be non-overlapping, however, as PFN2 is not required for blastopore closure in Xenopus but instead contributes to convergent extension (Khadka et al, 2009).
