Dynamic distribution of chemoattractant receptors in living cells during chemotaxis and persistent stimulation

J Cell Biol. 1997 Oct 20;139(2):365-74. doi: 10.1083/jcb.139.2.365.


While the localization of chemoattractant receptors on randomly oriented cells has been previously studied by immunohistochemistry, the instantaneous distribution of receptors on living cells undergoing directed migration has not been determined. To do this, we replaced cAR1, the primary cAMP receptor of Dictyostelium, with a cAR1-green fluorescence protein fusion construct. We found that this chimeric protein is functionally indistinguishable from wild-type cAR1. By time-lapse imaging of single cells, we observed that the receptors remained evenly distributed on the cell surface and all of its projections during chemotaxis involving turns and reversals of polarity directed by repositioning of a chemoattractant-filled micropipet. Thus, cell polarization cannot result from a gradient-induced asymmetric distribution of chemoattractant receptors. Some newly extended pseudopods at migration fronts showed a transient drop in fluorescence signals, suggesting that the flow of receptors into these zones may slightly lag behind the protrusion process. Challenge with a uniform increase in chemoattractant, sufficient to cause a dramatic decrease in the affinity of surface binding sites and cell desensitization, also did not significantly alter the distribution profile. Hence, the induced reduction in binding activity and cellular sensitivity cannot be due to receptor relocalization. The chimeric receptors were able to "cap" rapidly during treatment with Con A, suggesting that they are mobile in the plane of the cell membrane. This capping was not influenced by pretreatment with chemoattractant.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Cell Membrane / physiology
  • Cell Membrane / ultrastructure
  • Chemotaxis*
  • Cyclic AMP / pharmacology
  • Dictyostelium / cytology
  • Dictyostelium / drug effects
  • Dictyostelium / physiology*
  • GTP-Binding Proteins / physiology
  • Green Fluorescent Proteins
  • Luminescent Proteins / metabolism
  • Microscopy, Confocal
  • Phosphorylation
  • Receptors, Cyclic AMP / biosynthesis
  • Receptors, Cyclic AMP / isolation & purification
  • Receptors, Cyclic AMP / physiology*
  • Receptors, Formyl Peptide
  • Receptors, Immunologic / analysis
  • Receptors, Immunologic / physiology*
  • Receptors, Peptide / analysis
  • Receptors, Peptide / physiology*
  • Recombinant Fusion Proteins / isolation & purification
  • Recombinant Fusion Proteins / metabolism


  • Luminescent Proteins
  • Receptors, Cyclic AMP
  • Receptors, Formyl Peptide
  • Receptors, Immunologic
  • Receptors, Peptide
  • Recombinant Fusion Proteins
  • cyclic AMP receptor cAR1
  • Green Fluorescent Proteins
  • Cyclic AMP
  • GTP-Binding Proteins