ARFIP2 is a ubiquitously expressed protein implicated in mediating cross talk between RAC and ARF small GTPases. It has been shown that ARFIP2 binds specifically to GTP-bound ARF1 and ARF6, but binds to Rac-GTP and Rac-GDP with similar affinities. The X-ray structure of arfaptin reveals an elongated, crescent-shaped dimer of 3-helix coiled-coils. Structures of arfaptin with Rac bound to either GDP or the slowly hydrolysable analog GMPPNP show that the switch regions adopt similar conformations in both complexes.