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GTPase-activating proteins and their complexes
1Protein Structure Division, National Institute for Medical Research, London, UK. s-gambli@anika.nimr.mrc.ac.uk
Current Opinion in Structural Biology
|June 19, 1998
Summary
New crystallographic structures reveal how GTPase-activating proteins (GAPs) interact with G proteins. These findings enhance understanding of Rho and Ras family protein functions and their structural relationships.
Area of Science:
- Biochemistry
- Structural Biology
- Molecular Biology
Background:
- GTPase-activating proteins (GAPs) regulate G protein signaling pathways.
- Understanding GAP-G protein interactions is crucial for deciphering cellular communication.
- Previous structural data on these complexes were limited.
Purpose of the Study:
- To elucidate the structural basis of GAP-G protein interactions.
- To understand the mechanism by which GAPs modulate G protein activity.
- To compare the structures of RhoGAP and RasGAP complexes.
Main Methods:
- X-ray crystallography was used to determine the structures of four GAP-G protein complexes.
- Comparative structural analysis was performed on the determined complexes.
Main Results:
- Four novel crystallographic structures of GAP-G protein complexes were determined.
- GAPs specific for Rho and Ras families share a common mechanism involving arginine insertion and stabilization of switch regions.
- The structure of a heterotrimeric G protein complex revealed the activating protein does not directly participate in hydrolysis.
- Distinct structural features were observed between RhoGAP and RasGAP complexes.
Conclusions:
- The determined structures provide significant insights into GAP function and G protein regulation.
- A conserved mechanism exists for Rho and Ras GAPs, despite topological differences.
- Activating proteins for heterotrimeric G proteins have unique structural characteristics and roles.