A structure-based mechanism for Arf1-dependent recruitment of coatomer to membranes.

ABSTRACT: Budding of COPI-coated vesicles from Golgi membranes requires an Arf family G protein and the coatomer complex recruited from cytosol. Arf is also required with coatomer-related clathrin adaptor complexes to bud vesicles from the trans-Golgi network and endosomal compartments. To understand the structural basis for Arf-dependent recruitment of a vesicular coat to the membrane, we determined the structure of Arf1 bound to the ??-COP subcomplex of coatomer. Structure-guided biochemical analysis reveals that a second Arf1-GTP molecule binds to ??-COP at a site common to the ?- and ?-COP subunits. The Arf1-binding sites on coatomer are spatially related to PtdIns4,5P(2)-binding sites on the endocytic AP2 complex, providing evidence that the orientation of membrane binding is general for this class of vesicular coat proteins. A bivalent GTP-dependent binding mode has implications for the dynamics of coatomer interaction with the Golgi and for the selection of cargo molecules.

SUBMITTER: Yu X 

PROVIDER: S-EPMC3285272 | biostudies-literature | 2012 Feb

REPOSITORIES: biostudies-literature