Related Experiment Videos
Phosphoisoprenoids modulate association of Rab geranylgeranyltransferase with REP-1.
N H Thomä1, A Iakovenko, R S Goody
1Department of Physical Biochemistry, Max-Planck-Institute for Molecular Physiology, Otto-Hahn-Strasse 11, 44227 Dortmund, Germany.
The Journal of Biological Chemistry
|October 25, 2001
Summary
Rab geranylgeranyltransferase (RabGGTase) prenylation of Rab proteins involves Rab Escort Protein (REP). This study reveals REP-1 can bind RabGGTase with high affinity when geranylgeranyl pyrophosphate (GGpp) is present, suggesting an alternative prenylation pathway.
Area of Science:
- Biochemistry
- Molecular Biology
- Cellular Processes
Background:
- Rab geranylgeranyltransferase (RabGGTase) mediates Rab protein prenylation.
- Rab proteins require Rab Escort Protein (REP) for substrate recognition.
- The classical prenylation model involves Rab.REP complex formation before RabGGTase binding.
Purpose of the Study:
- To investigate the interaction between RabGGTase, REP-1, and geranylgeranyl pyrophosphate (GGpp).
- To elucidate the assembly pathway of the prenylation machinery.
- To determine the kinetic competence of a RabGGTase.GGpp.REP-1 complex.
Main Methods:
- Affinity precipitations
- Gel filtration
- Fluorescence assays
- Kinetic analysis of binding and prenylation rates
Main Results:
- REP-1 binds RabGGTase independently of Rab proteins.
- Geranylgeranyl pyrophosphate (GGpp) significantly enhances the RabGGTase-REP-1 interaction (Kd ~10 nm).
- Rab7 binding to the RabGGTase.GGpp.REP-1 complex occurs without REP-1 dissociation, forming a kinetically competent intermediate.
Conclusions:
- The GGpp-dependent RabGGTase-REP-1 complex represents a novel, kinetically competent intermediate in Rab prenylation.
- This finding suggests an alternative pathway for prenylation machinery assembly in vivo.
- The role of REP-1 in prenylation may involve direct interaction with RabGGTase facilitated by GGpp.