title: GAT (GGA and Tom1) domain responsible for ubiquitin binding and ubiquitination.
abstract: GGAs (Golgi-localizing, gamma-adaptin ear domain homology, ADP-ribosylation factor (ARF)-binding proteins) are a family of monomeric adaptor proteins involved in membrane trafficking from the trans-Golgi network to endosomes. The GAT (GGA and Tom1) domains of GGAs have previously been shown to interact with GTP-bound ARF and to be crucial for membrane recruitment of GGAs. Here we show that the C-terminal subdomain of the GAT domain, which is distinct from the N-terminal GAT subdomain responsible for ARF binding, can bind ubiquitin. The binding is mediated by interactions between residues on one side of the alpha3 helix of the GAT domain and those on the so-called Ile-44 surface patch of ubiquitin. The binding of the GAT domain to ubiquitin can be enhanced by the presence of a GTP-bound form of ARF. Furthermore, GGA itself is ubiquitinated in a manner dependent on the GAT-ubiquitin interaction. These results delineate the molecular basis for the interaction between ubiquitin and GAT and suggest that GGA-mediated trafficking is regulated by the ubiquitin system as endosomal trafficking mediated by other ubiquitin-binding proteins.
authors.affiliation: Institute of Biological Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8572, Japan.
authors.forename: Yoko
authors.initials: Y
authors.lastname: Shiba
authors.forename: Yohei
authors.initials: Y
authors.lastname: Katoh
authors.forename: Tomoo
authors.initials: T
authors.lastname: Shiba
authors.forename: Kaori
authors.initials: K
authors.lastname: Yoshino
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Takatsu
authors.forename: Hiromi
authors.initials: H
authors.lastname: Kobayashi
authors.forename: Hye-Won
authors.initials: HW
authors.lastname: Shin
authors.forename: Soichi
authors.initials: S
authors.lastname: Wakatsuki
authors.forename: Kazuhisa
authors.initials: K
authors.lastname: Nakayama
mesh_terms: D000595:Amino Acid Sequence; D001921:Brain / Q000378:metabolism; D018076:DNA, Complementary / Q000378:metabolism; D003902:Detergents / Q000494:pharmacology; D011992:Endosomes / Q000378:metabolism; D015723:Gene Library; D005982:Glutathione Transferase / Q000378:metabolism; D006801:Humans; D007532:Isoleucine / Q000737:chemistry; D008856:Microscopy, Fluorescence; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation; D010957:Plasmids / Q000378:metabolism; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D020798:Two-Hybrid System Techniques; D025801:Ubiquitin / Q000737:chemistry* / Q000378:metabolism
chemical_list: D018076:DNA, Complementary; D003902:Detergents; D011993:Recombinant Fusion Proteins; D025801:Ubiquitin; D007532:Isoleucine; D005982:Glutathione Transferase