Receptor-dependent G-protein activation in lipidic cubic phase

Javier Navarro, Ehud M. Landau, Karim Fahmy

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

The primary step in cellular signaling by G-protein-coupled receptors (GPCRs) is the interaction of the agonist-activated transmembrane receptor with an intracellular G-protein. Understanding the underlying molecular mechanisms requires the structural determination of receptor G-protein complexes that are not yet achieved. The crystal structure of the bovine photoreceptor rhodopsin, a prototypical GPCR, was solved recently and the structures of different states of engineered G-proteins were reported. Posttranslational hydrophobic modifications of G-proteins are in most cases removed for crystallization but play functional roles for interactions among G-protein subunits with receptors, as well as membranes. Bovine rhodopsin is reconstituted into lipidic cubic phases to assess their potential for crystallization of receptor G-protein complexes under conditions that may preserve the structural and functional roles of hydrophobic protein modifications. Three-dimensional bilayers of a bicontinuous lipidic cubic phase are successfully employed for crystallization of membrane and soluble proteins. UV-visible absorption and attenuated total reflection Fourier transform IR difference spectroscopy reveal that light activation of cubic phase reconstituted rhodopsin results in the generation of a metarhodopsin II-like state. Via diffusion along aqueous channels, transducin couples efficiently to this photoproduct as evidenced by the nucleotide-dependent increase of transducin fluorescence. Thus, rhodopsin transducin interactions do not crucially depend on the presence of snl and sn2 acyl chains, phospholipid head groups, or membrane planarity. Because lipidic cubic phases preserve the essential functional and structural properties of native rhodopsin and transducin, they appear suitable for the detergent-free crystallization of receptor G-protein complexes carrying a normal pattern of hydrophobic modifications.

Original languageEnglish (US)
Pages (from-to)167-177
Number of pages11
JournalBiopolymers - Biospectroscopy Section
Volume67
Issue number3
DOIs
StatePublished - 2002

Fingerprint

GTP-Binding Proteins
Rhodopsin
Transducin
Chemical activation
Proteins
Crystallization
G-Protein-Coupled Receptors
Membranes
Cell signaling
Protein Subunits
Fourier Analysis
Post Translational Protein Processing
Detergents
Structural properties
Phospholipids
Spectrum Analysis
Fourier transforms
Membrane Proteins
Nucleotides
Crystal structure

Keywords

  • G-protein
  • Lipid cubic phase
  • Receptor

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)
  • Biochemistry
  • Biophysics

Cite this

Receptor-dependent G-protein activation in lipidic cubic phase. / Navarro, Javier; Landau, Ehud M.; Fahmy, Karim.

In: Biopolymers - Biospectroscopy Section, Vol. 67, No. 3, 2002, p. 167-177.

Research output: Contribution to journalArticle

Navarro, Javier ; Landau, Ehud M. ; Fahmy, Karim. / Receptor-dependent G-protein activation in lipidic cubic phase. In: Biopolymers - Biospectroscopy Section. 2002 ; Vol. 67, No. 3. pp. 167-177.
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