Src-dependent phosphorylation of beta2-adaptin dissociates the beta-arrestin-AP-2 complex

J Cell Sci. 2007 May 15;120(Pt 10):1723-32. doi: 10.1242/jcs.03444. Epub 2007 Apr 24.

Abstract

Beta-arrestins are known to act as endocytic adaptors by recruiting the clathrin adaptor protein 2 (AP-2) complex to G-protein-coupled receptors (GPCRs), linking them to clathrin-coated pits (CCPs) for internalization. They also act as signaling molecules connecting GPCRs to different downstream effectors. We have previously shown that stimulation of the angiotensin II (Ang II) type 1 receptor (AGTR1, hereafter referred to as AT1R), a member of the GPCR family, promotes the formation of a complex between beta-arrestin, the kinase Src and AP-2. Here, we report that formation of such a complex is involved in the AT1R-mediated tyrosine phosphorylation of beta2-adaptin, the subunit of AP-2 involved in binding beta-arrestin. We identify a crucial tyrosine residue in the ear domain of beta2-adaptin and show in vitro that the phosphorylation of this site regulates the interaction between beta-arrestin and beta2-adaptin. Using fluorescently tagged proteins combined with resonance energy transfer and image cross-correlation spectroscopy approaches, we show in live cells that beta2-adaptin phosphorylation is an important regulatory process for the dissociation of beta-arrestin-AP-2 complexes in CCPs. Finally, we show that beta2-adaptin phosphorylation is involved in the early steps of receptor internalization. Our findings not only unveil beta2-adaptin as a new Src target during AT1R internalization, but also support the role of receptor-mediated signaling in the control of clathrin-dependent endocytosis of receptors.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adaptor Protein Complex 2 / metabolism*
  • Adaptor Protein Complex beta Subunits / chemistry
  • Adaptor Protein Complex beta Subunits / metabolism*
  • Animals
  • Arrestins / metabolism*
  • Binding Sites / physiology
  • COS Cells
  • Cell Line
  • Cell Membrane / metabolism
  • Chlorocebus aethiops
  • Clathrin-Coated Vesicles / metabolism
  • Endocytosis / physiology*
  • Humans
  • Phosphorylation
  • Protein Structure, Tertiary / physiology
  • Receptor, Angiotensin, Type 1 / metabolism
  • Receptors, Cell Surface / metabolism*
  • Receptors, Cell Surface / ultrastructure
  • Signal Transduction / physiology
  • Tyrosine / metabolism
  • beta-Arrestins
  • src-Family Kinases / metabolism*

Substances

  • Adaptor Protein Complex 2
  • Adaptor Protein Complex beta Subunits
  • Arrestins
  • Receptor, Angiotensin, Type 1
  • Receptors, Cell Surface
  • beta-Arrestins
  • Tyrosine
  • src-Family Kinases