Oral Presentation 2014 International Biophysics Congress

Visualizing GPCRs at the single molecule level to reveal subtleties of signaling mechanisms (#19)

Anthony Watts 1
  1. Biomembrane Structure Unit, Biochemistry Department, University of Oxford, Oxford, UK

Evidence is gatehring that GPCRs may use oligomerization as a means of determining coupling to downstream processes. Few generalized rules currently exist for defining or understanding GPCR oligomerization. Equally, direct methods for understanding how these receptors cross-react in membranes, or how the lipid composition can determine oliogmerization for purified receptors, are sparse. We have shown that a class A, ligand activated GPCR (neurotensin type 1 receptor, NTS1) is a constituitive dimer in well controlled lipid membranes, from studies of ligand binding and G-protein activation. Ensemble FRET reveals the lipid specificity of dimer formation, and single molecule FRET and ESR DEER studies show stochastic variability of both dimer formation and stability, as well as of the life-time of the complex. A stable and well defined dimer interface cannot be described in static terms, and it appears that significant dynamics of interfacial interactions exist (with dimer life-times ~ ms), but discrete sites (helices) of interaction are quite variable.

  1. Goddard, A., Dijkman, P., Adamson, R., Watts, A. (2013) Lipid-Dependent GPCR Dimerization. In P. Michael Conn, editors: Receptor-Receptor Interactions, Vol 117, MCB, UK: Academic Press, pp. 341-357.
  2. Oates, J., Faust, B., Attrill, H., Harding, P., Orwick, M., Watts, A. (2012) The role of cholesterol on the activity and stability of neurotensin receptor 1. BBA - Biomembranes, 1818, 2228-33.
  3. Oates, J. and Watts, A. (2011) Uncovering the intimate relationship between lipids, cholesterol and GPCR activation", Current Opinions in Structural Biology, 21:802-807.
  4. Harding, P.J., Attrill, H.A., Boehringer, J., Ross, S., Wadhams, G.H., Smith, E., Armitage, J.P. and Watts, A.(2009) Constitutive dimerisation of the GPCR, neurotensin receptor 1, reconstituted into phospholipid bilayers. Biophys. J., 96, 964-973.
  5. See also: (http://www.bioch.ox.ac.uk/~awatts)