Ena/VASP[Edit]
Proteins of the Ena/VASP family contribute to cell movement, axon guidance, neural tube closure and shape change in vertebrate cells by modulating actin filament organization and dynamics; these effects are achieved in part by regulating the morphology and behavior of actin-based structures such as lamellipodia and filopodia (reviewed in [1]). Ena/VASP proteins also modulate actin dynamics at sites of cell-ECM and cell-cell interactions and they are concentrated to the proximal portion of phosphotyrosine-rich domains at the ends of F-actin stress fibers [2]
Ena/VASP proteins promote actin filament elongation by tethering actin filaments to sites of active actin assembly [3, 4, 5]. Ena/VASP proteins recruit actin nucleation and initiation factors (e.g. Arp2/3 complex, formins) and promote F-actin assembly through profilin-binding (reviewed in [6]). The rate of Ena/VASP assisted actin filament elongation is determined by the recruitment of G-actin. This will occur via a G-actin binding site (GAB) that lies within the EVH2 domain and shares close sequence homology to WASP homology 2 motifs [7]. Ena/VASP proteins are also thought to accumulate at the plasma membrane where they alter actin polymerization by antagonizing the barbed (+) end capping proteins, thereby enabling the incorporation of actin into longer filaments [3, 4]; however, controversy over their exact mechanism still exists (reviewed in [1]). In addition, Ena/VASP may promote actin assembly by an unknown mechanism that is independent of initiation factors, however, this has not been demonstrated in intact cells [8]
Ena/VASP proteins promote actin filament elongation by tethering actin filaments to sites of active actin assembly [3, 4, 5]. Ena/VASP proteins recruit actin nucleation and initiation factors (e.g. Arp2/3 complex, formins) and promote F-actin assembly through profilin-binding (reviewed in [6]). The rate of Ena/VASP assisted actin filament elongation is determined by the recruitment of G-actin. This will occur via a G-actin binding site (GAB) that lies within the EVH2 domain and shares close sequence homology to WASP homology 2 motifs [7]. Ena/VASP proteins are also thought to accumulate at the plasma membrane where they alter actin polymerization by antagonizing the barbed (+) end capping proteins, thereby enabling the incorporation of actin into longer filaments [3, 4]; however, controversy over their exact mechanism still exists (reviewed in [1]). In addition, Ena/VASP may promote actin assembly by an unknown mechanism that is independent of initiation factors, however, this has not been demonstrated in intact cells [8]