The Bin/Amphiphysin/Rvs (BAR) domain of RhoGAP interacting with CIP4 homologs protein 1
BAR domains are dimerization, lipid binding and curvature sensing modules found in many different proteins with diverse functions. RhoGAP interacting with CIP4 homologs protein 1 (Rich1) is also called Neuron-associated developmentally-regulated protein (Nadrin) or Rho GTPase activating protein 17 (ARHGAP17). It is a Cdc42- and Rac-specific GAP that binds to polarity proteins through the scaffold protein angiomotin and plays a role in maintaining the integrity of tight junctions. It may be a component of a sorting mechanism in the recycling of tight junction transmembrane proteins. Rich1 contains an N-terminal BAR domain followed by a Rho GAP domain and a C-terminal proline-rich domain. It interacts with the BAR domain proteins endophilin and amphiphysin through its proline-rich region. The BAR domain of Rich1 forms oligomers and can bind membranes and induce membrane tubulation.