Epidermal growth factor-dependent phosphorylation of the GGA3 adaptor protein regulates its recruitment to membranes

Mol Cell Biol. 2005 Sep;25(18):7988-8000. doi: 10.1128/MCB.25.18.7988-8000.2005.

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.

MeSH terms

  • ADP-Ribosylation Factors / genetics
  • ADP-Ribosylation Factors / metabolism*
  • Adaptor Proteins, Vesicular Transport / genetics
  • Adaptor Proteins, Vesicular Transport / metabolism*
  • Amino Acid Sequence
  • Cells, Cultured
  • ErbB Receptors / metabolism*
  • Humans
  • Intracellular Membranes / metabolism*
  • Mitogen-Activated Protein Kinases / antagonists & inhibitors
  • Molecular Sequence Data
  • Mutation
  • Phosphoinositide-3 Kinase Inhibitors
  • Phosphorylation
  • Protein Transport
  • Signal Transduction

Substances

  • Adaptor Proteins, Vesicular Transport
  • GGA adaptor proteins
  • Phosphoinositide-3 Kinase Inhibitors
  • ErbB Receptors
  • Mitogen-Activated Protein Kinases
  • ADP-Ribosylation Factors