Two modes of interaction between the membrane-embedded TARP stargazin's C-terminal domain and the bilayer visualized by electron crystallography

J Struct Biol. 2011 Jun;174(3):542-51. doi: 10.1016/j.jsb.2011.03.012. Epub 2011 Mar 21.


Glutamate-mediated neurotransmission through ligand-gated, ionotropic glutamate receptors is the main form of excitatory neurotransmission in the vertebrate central nervous system where it plays central roles in learning, memory and a variety of disorders. Acting as auxiliary subunits, transmembrane α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid receptor (AMPAR) regulatory proteins (TARPs) are essential regulators for glutamate-mediated neurotransmission in the central nervous system. Here, we report the first electron crystallographic reconstructions of full-length mouse stargazin (γ-2) at ∼20Å resolution in a membrane bilayer environment. Formation of ordered arrays required anionic lipids and was modulated by cholesterol and monovalent cations. Projection structures revealed that the C-termini of stargazin monomers closely interacted with the bilayer surface in an extended conformation that placed the C-terminal PDZ-binding motif ∼100Å away from the transmembrane domain and in close proximity to a membrane re-entrant region. The C-termini interaction with the bilayer was modulated by the ionic strength of the solution and overall protein secondary structure increased when membrane-bound. Our data suggest that stargazin interactions with and within the membrane play significant roles in TARP structure and directly visualize TARP functional mechanisms essential for AMPAR trafficking and clustering.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Anions / chemistry
  • Calcium Channels / chemistry*
  • Calcium Channels / metabolism*
  • Calcium Channels / ultrastructure
  • Cholesterol / chemistry
  • Crystallography / methods*
  • Dimerization
  • Imaging, Three-Dimensional
  • Lipid Bilayers / chemistry*
  • Lipid Bilayers / metabolism*
  • Lipids / chemistry
  • Mice
  • PDZ Domains
  • Protein Structure, Tertiary
  • Receptors, AMPA / chemistry
  • Receptors, AMPA / metabolism


  • Anions
  • Cacng2 protein, mouse
  • Calcium Channels
  • Lipid Bilayers
  • Lipids
  • Receptors, AMPA
  • Cholesterol