RIN2-RAGST (residues 785-879) protein.RIN2, only expressed in neurons, preferentially interactswith the GTP form of Rab5 rather than the GDP form,although it enhances the guanine exchange reaction onRab5. Moreover, gel filtration and immunoprecipitationanalyses suggest that RIN2 could form a tetramer composed of anti-parallel linkage of two parallel dimers.These results suggest that RIN2 may function as an upstream activator and/or downstream effector for Rab5 inthe endocytic pathway. Additionally RIN2 interacts withseveral Ras proteins, it binds the GTP-loaded forms of HRas, TC21 and M-Ras. Purity >95% by SDS-PAGE