title: RhoBTB3: a Rho GTPase-family ATPase required for endosome to Golgi transport.
abstract: Rho GTPases are key regulators of the actin-based cytoskeleton; Rab GTPases are key regulators of membrane traffic. We report here that the atypical Rho GTPase family member, RhoBTB3, binds directly to Rab9 GTPase and functions with Rab9 in protein transport from endosomes to the trans Golgi network. Gene replacement experiments show that RhoBTB3 function in cultured cells requires both RhoBTB3's N-terminal, Rho-related domain and C-terminal sequences that are important for Rab9 interaction. Biochemical analysis reveals that RhoBTB3 binds and hydrolyzes ATP rather than GTP. Rab9 binding opens the autoinhibited RhoBTB3 protein to permit maximal ATP hydrolysis. Because RhoBTB3 interacts with TIP47 on membranes, we propose that it may function to release this cargo selection protein from vesicles to permit their efficient docking and fusion at the Golgi.
authors.affiliation: Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305-5307, USA.
authors.forename: Eric J
authors.initials: EJ
authors.lastname: Espinosa
authors.forename: Monica
authors.initials: M
authors.lastname: Calero
authors.forename: Khambhampaty
authors.initials: K
authors.lastname: Sridevi
authors.forename: Suzanne R
authors.initials: SR
authors.lastname: Pfeffer
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000595:Amino Acid Sequence; D004268:DNA-Binding Proteins / Q000378:metabolism; D011992:Endosomes / Q000378:metabolism*; D006056:Golgi Apparatus / Q000378:metabolism*; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism; D008969:Molecular Sequence Data; D000070796:Perilipin-3; D011257:Pregnancy Proteins / Q000378:metabolism; D021381:Protein Transport; D016415:Sequence Alignment; D033921:Vesicular Transport Proteins; D020741:rho GTP-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: D004268:DNA-Binding Proteins; D047908:Intracellular Signaling Peptides and Proteins; C038196:PLIN3 protein, human; D000070796:Perilipin-3; D011257:Pregnancy Proteins; D033921:Vesicular Transport Proteins; D000255:Adenosine Triphosphate; C541346:RhoBTB3 protein, human; D020741:rho GTP-Binding Proteins