Structural aspects of the mechanism of action of Rab escort prot

Structural aspects of the mechanism of action of Rab escort protein and Rab-GDI in intracellular vesicular transport


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- Date/Time : Tue August 19., 2003


             14:00-15:00 

- Speaker : Roger S. Goody


            - Max-Planck-Institute for Molecular Physiology

    


- Place : Life Science Bldg. #104

- For inquires : Professor Yunje Cho Dept. of Life Science


                생명과학과 조윤제 교수 (☎279-2288)

Abstract -


 Rab family GTPases, key regulators of membrane targeting and fusion, require the covalent attachment of geranylgeranyl lipids to their C-termini for their function. The enzyme catalyzing the post-translational prenylation reaction (Rab GGTase) differs from other protein prenyltransferases in that it requires a protein cofactor (rab escort protein, or REP), which also serves to keep the modified protein in a soluble form and to chaperone it to the appropriate membrane. We have determined the 3D structure of REP-1 as a complex with Rab GGTase. The nature of the structure together with a docking model including a Rab protein bound to the region of the REP molecule identified by mutational studies as being the likely Rab binding site provides insight into the details of the prenylation reaction. To validate and refine the preliminary conclusions form this work, we have also determined the structures of both prenylated and unprenylated Rab molecules as complexes with REP and GDI (GDP dissociation inhibitor). The combined structural and kinetic information on these interactions provides explanations for the GDI effect and for the preferential interaction of REP/GDI with the GDP form of Rab proteins. It also provides a starting point for understanding targeting of the Rab proteins to specific membranes and throws further light onto mechanistic aspects of the prenylation reaction and the solubilizing properties of REP/GDI.