Evolving nature of the AP2 alpha-appendage hub during clathrin-coated vesicle endocytosis

EMBO J. 2004 Nov 10;23(22):4371-83. doi: 10.1038/sj.emboj.7600445. Epub 2004 Oct 21.

Abstract

Clathrin-mediated endocytosis involves the assembly of a network of proteins that select cargo, modify membrane shape and drive invagination, vesicle scission and uncoating. This network is initially assembled around adaptor protein (AP) appendage domains, which are protein interaction hubs. Using crystallography, we show that FxDxF and WVxF peptide motifs from synaptojanin bind to distinct subdomains on alpha-appendages, called 'top' and 'side' sites. Appendages use both these sites to interact with their binding partners in vitro and in vivo. Occupation of both sites simultaneously results in high-affinity reversible interactions with lone appendages (e.g. eps15 and epsin1). Proteins with multiple copies of only one type of motif bind multiple appendages and so will aid adaptor clustering. These clustered alpha(appendage)-hubs have altered properties where they can sample many different binding partners, which in turn can interact with each other and indirectly with clathrin. In the final coated vesicle, most appendage binding partners are absent and thus the functional status of the appendage domain as an interaction hub is temporal and transitory giving directionality to vesicle assembly.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adaptor Protein Complex 2 / chemistry
  • Adaptor Protein Complex 2 / genetics
  • Adaptor Protein Complex 2 / metabolism*
  • Amino Acid Motifs
  • Animals
  • Binding Sites
  • COS Cells
  • Chlorocebus aethiops
  • Clathrin / metabolism*
  • Clathrin-Coated Vesicles / metabolism*
  • Crystallography, X-Ray
  • Endocytosis*
  • Enzyme Inhibitors / chemistry
  • Enzyme Inhibitors / metabolism
  • Ligands
  • Mass Spectrometry
  • Models, Biological
  • Models, Molecular
  • Mutagenesis, Site-Directed
  • Nerve Tissue Proteins / chemistry
  • Nerve Tissue Proteins / metabolism
  • Phosphoric Monoester Hydrolases / chemistry
  • Phosphoric Monoester Hydrolases / metabolism
  • Protein Binding
  • Protein Structure, Tertiary
  • Proteomics
  • Rats
  • Water / chemistry

Substances

  • Adaptor Protein Complex 2
  • Clathrin
  • Enzyme Inhibitors
  • Ligands
  • Nerve Tissue Proteins
  • Water
  • synaptojanin
  • Phosphoric Monoester Hydrolases