title: Arf, Arl, Arp and Sar proteins: a family of GTP-binding proteins with a structural device for 'front-back' communication.
abstract: Arf proteins are important regulators of cellular traffic and the founding members of an expanding family of homologous proteins and genomic sequences. They depart from other small GTP-binding proteins by a unique structural device, which we call the 'interswitch toggle', that implements front-back communication from the N-terminus to the nucleotide binding site. Here we define the sequence and structural determinants that propagate information across the protein and identify them in all of the Arf family proteins other than Arl6 and Arl4/Arl7. The positions of these determinants lead us to propose that Arf family members with the interswitch toggle device are activated by a bipartite mechanism acting on opposite sides of the protein. The presence of this communication device might provide a more useful basis for unifying Arf homologs as a family than do the cellular functions of these proteins, which are mostly unrelated. We review available genomic sequences and functional data from this perspective, and identify a novel subfamily that we call Arl8.
authors.affiliation: Laboratoire d'Enzymologie et Biochimie Structurales, UPR 9063 CNRS, 1 avenue de la Terrasse, 91198 Gif sur Yvette cedex, France.
authors.forename: Sebastiano
authors.initials: S
authors.lastname: Pasqualato
authors.forename: Louis
authors.initials: L
authors.lastname: Renault
authors.forename: Jacqueline
authors.initials: J
authors.lastname: Cherfils
mesh_terms: D000089982:ADP-Ribosylation Factor 6; D020727:ADP-Ribosylation Factors / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D020558:GTP Phosphohydrolases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000378:metabolism; D006801:Humans; D008565:Membrane Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D020559:Monomeric GTP-Binding Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D011487:Protein Conformation; D016415:Sequence Alignment
chemical_list: D000089982:ADP-Ribosylation Factor 6; D008565:Membrane Proteins; C086264:SAR protein, Lycopersicon esculentum; D006160:Guanosine Triphosphate; C097313:ADP-ribosylation factor related proteins; D020558:GTP Phosphohydrolases; D020727:ADP-Ribosylation Factors; D020559:Monomeric GTP-Binding Proteins