title: Epidermal growth factor-dependent phosphorylation of the GGA3 adaptor protein regulates its recruitment to membranes.
abstract: The Golgi-localized, Gamma-ear-containing, Arf-binding (GGA) proteins are monomeric clathrin adaptors that mediate the sorting of transmembrane cargo at the trans-Golgi network and endosomes. Here we report that one of these proteins, GGA3, becomes transiently phosphorylated upon activation of the epidermal growth factor (EGF) receptor. This phosphorylation takes place on a previously unrecognized site in the "hinge" segment of the protein, S368, and is strictly dependent on the constitutive phosphorylation of another site, S372. The EGF-induced phosphorylation of S368 does not require internalization of the EGF receptor or association of GGA3 with membranes. This phosphorylation can be blocked by inhibitors of both the mitogen-activated protein kinase and phosphatidylinositol 3-kinase pathways that function downstream of the activated EGF receptor. Phosphorylation of GGA3 on S368 causes an increase in the hydrodynamic radius of the protein, indicating a transition to a more asymmetric shape. Mutation of S368 and S372 to a phosphomimic aspartate residue decreases the association of GGA3 with membranes. These observations indicate that EGF signaling elicits phosphorylation events that regulate the association of GGA3 with organellar membranes.
authors.affiliation: Cell Biology and Metabolism Branch, National Institute of Child Health and Human Development, Building 18T/Room 101, National Institutes of Health, Bethesda, MD 20892, USA.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Kametaka
authors.forename: Rafael
authors.initials: R
authors.lastname: Mattera
authors.forename: Juan S
authors.initials: JS
authors.lastname: Bonifacino
mesh_terms: D020727:ADP-Ribosylation Factors / Q000235:genetics / Q000378:metabolism*; D033942:Adaptor Proteins, Vesicular Transport / Q000235:genetics / Q000378:metabolism*; D000595:Amino Acid Sequence; D002478:Cells, Cultured; D066246:ErbB Receptors / Q000378:metabolism*; D006801:Humans; D007425:Intracellular Membranes / Q000378:metabolism*; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors; D008969:Molecular Sequence Data; D009154:Mutation; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010766:Phosphorylation; D021381:Protein Transport; D015398:Signal Transduction
chemical_list: D033942:Adaptor Proteins, Vesicular Transport; C407306:GGA adaptor proteins; D000081082:Phosphoinositide-3 Kinase Inhibitors; D066246:ErbB Receptors; D020928:Mitogen-Activated Protein Kinases; D020727:ADP-Ribosylation Factors