The Structure of an Arf-ArfGAP Complex Reveals a Ca2+ Regulatory Mechanism
Copyright policy )The Structure of an Arf-ArfGAP Complex Reveals a Ca2+ Regulatory Mechanism
Arfs are small G proteins that have a key role in vesicle trafficking and cytoskeletal remodeling. ArfGAP proteins stimulate Arf intrinsic GTP hydrolysis by a mechanism that is still unresolved. Using a fusion construct we solved the structure of the ArfGAP ASAP3 in complex with Arf6 in the transition state. This structure clarifies the ArfGAP catalytic mechanism and shows a glutamine((Arf6)) and an arginine finger((ASAP3)) as the important catalytic residues. Unexpectedly the structure shows a calcium ion, liganded by both proteins in the complex interface, stabilizing the interaction and orienting the catalytic machinery. Calcium stimulates the GAP activity of ASAPs, but not other members of the ArfGAP family. This type of regulation is unique for GAPs and any other calcium-regulated processes and hints at a crosstalk between Ca(2+) and Arf signaling.
- Max Planck Society Germany
- Max Planck Institute of Molecular Physiology Germany
Models, Molecular, PROTEINS, Biochemistry, Genetics and Molecular Biology(all), ADP-Ribosylation Factors, GTPase-Activating Proteins, Molecular Sequence Data, Crystallography, X-Ray, SIGNALING, ADP-Ribosylation Factor 6, Humans, CELLBIO, Calcium, Protein Interaction Domains and Motifs, Amino Acid Sequence, Guanosine Triphosphate, Sequence Alignment
Models, Molecular, PROTEINS, Biochemistry, Genetics and Molecular Biology(all), ADP-Ribosylation Factors, GTPase-Activating Proteins, Molecular Sequence Data, Crystallography, X-Ray, SIGNALING, ADP-Ribosylation Factor 6, Humans, CELLBIO, Calcium, Protein Interaction Domains and Motifs, Amino Acid Sequence, Guanosine Triphosphate, Sequence Alignment
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