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Rapid hop diffusion of a G-protein-coupled receptor in the plasma membrane as revealed by single-molecule techniques

Kenichi Suzuki1, Ken Ritchie, Eriko Kajikawa

  • 1Kusumi Membrane Organizer Project, Exploratory Research for Advanced Technology Organization, Department of Biological Science and Institute for Advanced Research, Nagoya University, Nagoya 464-8602, Japan.

Biophysical Journal
|February 1, 2005
PubMed

Insights

The mu-opioid receptor (muOR) rapidly diffuses between membrane compartments, challenging previous confinement theories. This hop diffusion suggests G-protein coupled receptors follow the fence and picket models of membrane organization.

Area of Science:

  • Cell Biology
  • Biophysics
  • Membrane Dynamics

Background:

  • G-protein coupled receptors (GPCRs) play crucial roles in cellular signaling.
  • Understanding the membrane diffusion dynamics of GPCRs, like the mu-opioid receptor (muOR), is key to elucidating their function.
  • Previous studies suggested restricted diffusion of muOR within specific membrane domains.

Purpose of the Study:

  • To investigate the diffusion dynamics of the mu-opioid receptor (muOR) in the plasma membrane.
  • To determine if muOR diffusion is confined or exhibits more dynamic behavior.
  • To explore the potential applicability of the fence and picket models to GPCR membrane mobility.

Main Methods:

  • Single-fluorescent molecule video imaging.
  • High-speed single-particle tracking (SPT) of gold-labeled muOR.
  • Analysis of muOR trajectories to determine diffusion patterns and compartment sizes.

Main Results:

  • Mu-opioid receptor (muOR) exhibits rapid hop diffusion across nested membrane compartments (210-nm and 730-nm).
  • Diffusion rates are comparable to the transferrin receptor, suggesting similar membrane mobility mechanisms.
  • Prolonged on-ice preincubation of gold probes can induce artificial confinement, a technique to be avoided in future SPT studies.
  • Actin filaments likely define the boundaries of these membrane compartments.

Conclusions:

  • The mu-opioid receptor (muOR) is not rigidly confined but undergoes hop diffusion, supporting the fence and picket models for GPCRs.
  • Actin-based membrane skeleton structures play a significant role in compartmentalizing the plasma membrane for GPCRs.
  • Methodological artifacts, such as prolonged on-ice incubation, can significantly impact SPT results and should be carefully controlled.

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