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Cell. 1999 Mar 19;96(6):893-902.

Structural and functional analysis of the ARF1-ARFGAP complex reveals a role for coatomer in GTP hydrolysis.

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1
Cellular Biochemistry and Biophysics Program, Memorial Sloan-Kettering Cancer Center, New York, New York 10021, USA. jonathan@ximpact4.ski.mskcc.org

Abstract

The crystal structure of the complex of ARF1 GTPase bound to GDP and the catalytic domain of ARF GTPase-activating protein (ARFGAP) has been determined at 1.95 A resolution. The ARFGAP molecule binds to switch 2 and helix alpha3 to orient ARF1 residues for catalysis, but it supplies neither arginine nor other amino acid side chains to the GTPase active site. In the complex, the effector-binding region appears to be unobstructed, suggesting that ARFGAP could stimulate GTP hydrolysis while ARF1 maintains an interaction with its effector, the coatomer complex of COPI-coated vesicles. Biochemical experiments show that coatomer directly participates in the GTPase reaction, accelerating GTP hydrolysis a further 1000-fold in an ARFGAP-dependent manner. Thus, a tripartite complex controls the GTP hydrolysis reaction triggering disassembly of COPI vesicle coats.

PMID:
10102276
[Indexed for MEDLINE]
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