Identification of profilin and src homology 3 domains as binding partners for Drosophila enabled

Drosophila Enabled (Ena) was first identified as a genetic suppressor of mu tations in the Abelson tyrosine kinase and subsequently was shown to be a m ember of the Ena/vasodilator-stimulated phosphoprotein family of proteins. All members of this family have a conserved domain organization, bind the f ocal adhesion protein zyxin, and localize to focal adhesions and stress fib ers. Members of this family are thought to be involved in the regulation of cytoskeleton dynamics. The Ena protein sequence has multiple poly(L-prolin e) residues with similarity to both profilin and src homology 3 binding sit es. Here, we show that Ena can bind directly to the Drosophila homolog of p rofilin, chickadee. Furthermore, Ena and profilin were colocalized in sprea ding cultured cells. We report that the proline-rich region of Ena is respo nsible for this interaction as well as for mediating binding to the src hom ology 3 domain of the Abelson tyrosine kinase. These data support the hypot hesis that Ena provides a regulated link between signal transduction and cy toskeleton assembly in the developing Drosophila embryo.