Identification of specific protein regions involved in the regulation of the Diaphanous‐related Formin, DAAM1

Abstract

Diaphanous-related formins (DRF) are a conserved family of proteins that are involved in the coordination of the cytoskeleton. Based on studies of yeast and mammalian DRF proteins, the regulation of DRFs are dependent on the mechanism of autoinhibition; the Dia-autoregulatory domain (DAD) binds to the Diaphanous inhibitory domain (DID), keeping the DRF inactive until Rho GTPases binds to the GTPase Binding Domain (GBD) and releases the DAD from DID, thereby activating the DRF protein. Since DID-DAD binding plays an important role in dictating the regulation of DRFs, our laboratory has focused on elucidating the autoregulatory regions in another DRF family member, DAAM1 (Dishevelled-associated activator of morphogenesis). Known to interact with the GTPases RhoA and Cdc42, DAAM1 has also been shown to work with Src in the formation of branched protrusions of the cell. Here, we have used a combination of somatic cell microinjection, immunofluorescence, and fluorescence anisotropy to elucidate the specific regions involved in the autoregulation of DAAM1. In addition, we have identified a specific residue in the DAD region that may play a pivotal role in DAAM1 autoregulation.