Ral: mediator of membrane trafficking.
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.
van Dam
Ellen M
EM
Cell Signalling Unit, Children's Medical Research Institute, Locked Bag 23, Wentworthville, NSW 2145, Australia.
Robinson
Phillip J
PJ
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*
D020725:ral GTP-Binding Proteins