title: Heterotrimeric G proteins interact with the small GTPase ARF. Possibilities for the regulation of vesicular traffic.
abstract: Trimeric G proteins have emerged as important regulators of membrane trafficking. To explore a role for G beta gamma in endosome fusion, we have taken advantage of beta-adrenergic receptor kinase (beta ARK), an enzyme translocated to membranes by interaction with G beta gamma. The COOH terminus of beta ARK (beta ARKct) has a G beta gamma-binding domain which blocks some G beta gamma-mediated processes. We found that beta ARKct and peptide G, a peptide derived from beta ARKct, inhibit in vitro endosome fusion. Interestingly, peptide G and ARF share sequence similarity. Peptide G and beta ARKct reversed ARF-mediated inhibition of endosome fusion and blocked ARF binding to membranes. Using an ARF fusion protein, we show that both G beta gamma and G alpha s interact with the small GTPase ARF, an interaction that is regulated by nucleotide binding. We conclude that G proteins may participate in the regulation of vesicular trafficking by directly interacting with ARF, a cytosolic factor required for transport.
authors.affiliation: Department of Cell Biology and Physiology, Washington University, School of Medicine, St. Louis, Missouri 63110, USA.
authors.forename: M I
authors.initials: MI
authors.lastname: Colombo
authors.forename: J
authors.initials: J
authors.lastname: Inglese
authors.forename: C
authors.initials: C
authors.lastname: D'Souza-Schorey
authors.forename: W
authors.initials: W
authors.lastname: Beron
authors.forename: P D
authors.initials: PD
authors.lastname: Stahl
mesh_terms: D020727:ADP-Ribosylation Factors; D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D002462:Cell Membrane; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D004705:Endocytosis; D019204:GTP-Binding Proteins / Q000737:chemistry / Q000378:metabolism*; D005982:Glutathione Transferase / Q000378:metabolism; D006706:Homeostasis; D046911:Macromolecular Substances; D008264:Macrophages; D008561:Membrane Fusion; D008969:Molecular Sequence Data; D015388:Organelles / Q000502:physiology; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D017384:Sequence Deletion; D017386:Sequence Homology, Amino Acid; D051552:beta-Adrenergic Receptor Kinases
chemical_list: D046911:Macromolecular Substances; D011993:Recombinant Fusion Proteins; D005982:Glutathione Transferase; D017868:Cyclic AMP-Dependent Protein Kinases; D051552:beta-Adrenergic Receptor Kinases; D019204:GTP-Binding Proteins; D020727:ADP-Ribosylation Factors