Abstract: The present invention relates to crystalline Rab9 in complex with either GDP or the GTP analog Guanosine 5?-(?,?-imido) triphosphate (GppNHp), the three dimensional coordinates and structures of Rab9 in Rab9-GDP and Rab9-GppNHp complexes, and uses thereof for drug design. In particular, the present invention relates to methods for producing Rab9 crystals of sufficient quality to obtain a determination of the three dimensional structure of Rab9 to a high resolution in both its GTP-bound (on/active) and GDP-bound (off/inactive) conformations. The present invention also relates to a computer-readable medium encoded with the three dimensional coordinates of Rab9 in Rab9-GDP and Rab9-GppNHp complexes wherein, using a graphical display software program, the three dimensional coordinates create an electronic file that can be visualized on a computer capable of representing the electronic file as a three dimensional image.