title: Ral: mediator of membrane trafficking.
abstract: Ral is a multifunctional small GTPase involved in tumorigenesis and in controlling intracellular membrane trafficking. It is mainly activated by factors downstream of Ras, or independently of these factors and operates by protein-protein interactions with an expanding repertoire of partners. RalA is a positive regulator of calcium-evoked exocytosis via binding phospholipase D and is involved in G protein coupled receptor signalling by binding phospholipase C-delta1. The binding of Ral to calmodulin links to intracellular trafficking events. Another link is direct binding of activated Ral (Ral-GTP) to the endocytic and exocytic machineries. Ral-GTP binds RalBP1, which connects to receptor-mediated endocytosis via AP-2. Alternatively, Ral-GTP binds the exocyst complex, which controls secretory vesicle trafficking in regulated secretion and filopodia formation. Thus, Ral-GTP "chooses" between different membrane trafficking pathways. Other Ral partners are still being uncovered that may provide further mechanistic insights into how Ral controls diverse membrane trafficking pathways.
authors.affiliation: Cell Signalling Unit, Children's Medical Research Institute, Locked Bag 23, Wentworthville, NSW 2145, Australia.
authors.forename: Ellen M
authors.initials: EM
authors.lastname: van Dam
authors.forename: Phillip J
authors.initials: PJ
authors.lastname: Robinson
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001692:Biological Transport; D002462:Cell Membrane / Q000378:metabolism*; D006801:Humans; D008954:Models, Biological; D008969:Molecular Sequence Data; D011485:Protein Binding; D017386:Sequence Homology, Amino Acid; D020725:ral GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*
chemical_list: D020725:ral GTP-Binding Proteins