The interaction of beta-arrestin with the AP-2 adaptor is required for the clustering of beta 2-adrenergic receptor into clathrin-coated pits

J Biol Chem. 2000 Jul 28;275(30):23120-6. doi: 10.1074/jbc.M002581200.

Abstract

Beta-arrestins are cytosolic proteins that regulate the signaling and the internalization of G protein-coupled receptors (GPCRs). Although termination of receptor coupling requires beta-arrestin binding to agonist-activated receptors, GPCR endocytosis involves the coordinate interactions between receptor-beta-arrestin complexes and other endocytic proteins such as adaptor protein 2 (AP-2) and clathrin. Clathrin interacts with a conserved motif in the beta-arrestin C-terminal tail; however, the specific molecular determinants in beta-arrestin that bind AP-2 have not been identified. Moreover, the respective contributions of the interactions of beta-arrestin with AP-2 and clathrin toward the targeting of GPCRs to clathrin-coated vesicles have not been established. Here, we identify specific arginine residues (Arg(394) and Arg(396)) in the beta-arrestin 2 C terminus that mediate beta-arrestin binding to AP-2 and show, in vitro, that these domains in beta-arrestin 1 and 2 interact equally well with AP-2 independently of clathrin binding. We demonstrate in HEK 293 cells by fluorescence microscopy that beta(2)-adrenergic receptor-beta-arrestin complexes lacking the beta-arrestin-clathrin binding motif are still targeted to clathrin-coated pits. In marked contrast, receptor-beta-arrestin complexes lacking the beta-arrestin/AP-2 interactions are not effectively compartmentalized in punctated areas of the plasma membrane. These results reveal that the binding of a receptor-beta-arrestin complex to AP-2, not to clathrin, is necessary for the initial targeting of beta(2)-adrenergic receptor to clathrin-coated pits.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adaptor Protein Complex alpha Subunits
  • Adaptor Proteins, Vesicular Transport
  • Amino Acid Sequence
  • Arrestins / chemistry
  • Arrestins / metabolism*
  • Clathrin / metabolism*
  • Coated Pits, Cell-Membrane / metabolism*
  • Membrane Proteins / metabolism*
  • Molecular Sequence Data
  • Protein Binding
  • Receptors, Adrenergic, beta-2 / metabolism*
  • Sequence Homology, Amino Acid
  • beta-Arrestins

Substances

  • Adaptor Protein Complex alpha Subunits
  • Adaptor Proteins, Vesicular Transport
  • Arrestins
  • Clathrin
  • Membrane Proteins
  • Receptors, Adrenergic, beta-2
  • beta-Arrestins