title: Gamma-COP appendage domain - structure and function.
abstract: COPI-coated vesicles mediate retrograde transport from the Golgi back to the ER and intra-Golgi transport. The cytosolic precursor of the COPI coat, the heptameric coatomer complex, can be thought of as composed of two subcomplexes. The first consists of the beta-, gamma-, delta- and zeta-COP subunits which are distantly homologous to AP clathrin adaptor subunits. The second consists of the alpha-, beta'- and epsilon-COP subunits. Here, we present the structure of the appendage domain of gamma-COP and show that it has a similar overall fold as the alpha-appendage of AP2. Again, like the alpha-appendage the gamma-COP appendage possesses a single protein/protein interaction site on its platform subdomain. We show that in yeast this site binds to the ARFGAP Glo3p, and in mammalian gamma-COP this site binds to a Glo3p orthologue, ARFGAP2. On the basis of mutations in the yeast homologue of gamma-COP, Sec21p, a second binding site is proposed to exist on the gamma-COP appendage that interacts with the alpha,beta',epsilon COPI subcomplex.
authors.affiliation: Cambridge Institute for Medical Research & Department of Clinical Biochemistry, University of Cambridge, Hills Road, Cambridge CB2 2XY, UK.
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Watson
authors.forename: Gabriella
authors.initials: G
authors.lastname: Frigerio
authors.forename: Brett M
authors.initials: BM
authors.lastname: Collins
authors.forename: Rainer
authors.initials: R
authors.lastname: Duden
authors.forename: David J
authors.initials: DJ
authors.lastname: Owen
mesh_terms: D020727:ADP-Ribosylation Factors / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D020755:Coat Protein Complex I / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D018360:Crystallography, X-Ray; D005656:Fungal Proteins / Q000737:chemistry / Q000378:metabolism*; D020690:GTPase-Activating Proteins / Q000378:metabolism; D006801:Humans; D046911:Macromolecular Substances; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011485:Protein Binding; D011487:Protein Conformation; D017510:Protein Folding; D017434:Protein Structure, Tertiary; D021122:Protein Subunits / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D051381:Rats; D016415:Sequence Alignment; D022161:Transport Vesicles / Q000378:metabolism
chemical_list: D020755:Coat Protein Complex I; D005656:Fungal Proteins; D020690:GTPase-Activating Proteins; D046911:Macromolecular Substances; D021122:Protein Subunits; D020727:ADP-Ribosylation Factors