The F-BAR (FES-CIP4 Homology and Bin/Amphiphysin/Rvs) domain of Saccharomyces cerevisiae Rho GTPase activating protein Rgd1 and similar proteins.
F-BAR domains are dimerization modules that bind and bend membranes and are found in proteins involved in membrane dynamics and actin reorganization. Saccharomyces cerevisiae Rgd1 is a GTPase activating protein (GAP) with activity towards Rho3p and Rho4p, which are involved in bud growth and cytokinesis, respectively. At low pH, S. cerevisiae Rgd1 is required for cell survival and the activation of the protein kinase C pathway, which is important in cell integrity and the maintenance of cell shape. It contains an N-terminal F-BAR domain and a C-terminal Rho GAP domain. The F-BAR domain of S. cerevisiae Rgd1 binds to phosphoinositides and plays an important role in the localization of the protein to the bud tip/neck during the cell cycle. F-BAR domains form banana-shaped dimers with a positively-charged concave surface that binds to negatively-charged lipid membranes. They can induce membrane deformation in the form of long tubules.