 The function of the interaction between these two regions is presently unclear, but the structure implies a regulatory interaction that influences the helical-lid conformation in order to control ligand access to the lipid binding pocket.Through its NF1-GRD domain, neurofibromin increases the rate of GTP hydrolysis of Ras, and acts as a tumor suppressor by reducing Ras activity.When the Ras-Nf1 complex assembles, active Ras binds in a groove that is present in the neurofibromin catalytic domain.