Dynamic localization of G proteins in Dictyostelium discoideum

Carrie A. Elzie, Jennifer Colby, Morgan A. Sammons, Chris Janetopoulos

Research output: Contribution to journalArticlepeer-review

30 Scopus citations


Extracellular stimuli exert their effects on eukaryotic cells via serpentine G-protein-coupled receptors and mediate a vast number of physiological responses. Activated receptors stimulate heterotrimeric G-proteins, consisting of three subunits, α, β and γ. In Dictyostelium discoideum, cAMP binds to the cAMP receptor cAR1, which is coupled to the heterotrimer containing the Ga2 subunit. These studies provide in vivo evidence as to how receptors influence the localization of the G-protein complex prior to and after ligand binding. Previous work has shown that the state of the heterotrimer could be monitored by changes in fluorescence (or Förster) resonance energy transfer (FRET) between the α2- and β-subunits of D. discoideum. We now report the kinetics of G-protein activation as a loss of FRET prior to and after cAMP addition by using total internal reflection fluorescence microscopy (TIRFM). We also performed photobleaching experiments to measure G-protein recovery times. Our data show that inactive and active G-proteins cycle between the cytosol and plasma membrane. These data suggest that cAR1 activation slows the membrane dissociation ('off') rate of the α2 subunit, while simultaneously promoting βγ-subunit dissociation.

Original languageEnglish (US)
Pages (from-to)2597-2603
Number of pages7
JournalJournal of cell science
Issue number15
StatePublished - Aug 1 2009
Externally publishedYes


  • Chemotaxis
  • FRET
  • G proteins

ASJC Scopus subject areas

  • Cell Biology


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