Diffusion of Single-Pass Transmembrane Receptors: From the Plasma Membrane into Giant Liposomes

Remigiusz Worch, Zdenek Petrášek, Petra Schwille, Thomas Weidemann

Research output: Contribution to journalArticleResearchpeer-review

Abstract

To quantitatively examine the effect of membrane organization on lateral diffusion, we studied fluorescent carbocyanine lipid analogues and EGFP-tagged, single-pass transmembrane proteins in systems of decreasing complexity: (i) the plasma membrane (PM) of living cells, (ii) paraformaldehyde/dithiothreitol-induced giant plasma membrane vesicles (GPMVs), and (iii) giant unilamellar vesicles (GUVs) under physiological buffer conditions. A truncated, signaling-deficient interleukin-4 receptor subunit, showing efficient accumulation in the plasma membrane, served as a model transmembrane protein. Two-dimensional diffusion coefficients (D) were determined by fluorescence correlation spectroscopy (FCS) either at fixed positions (single-point, spFCS) or while scanning a circular orbit (circular scanning, csFCS). Consistent with a different inclusion sizes in the membrane, lipids diffuse slightly faster than the single-spanning membrane proteins in both membrane systems, GUVs and GPMVs. In GPMVs lipids and proteins consistently experienced a fivefold larger viscosity than in GUVs, reflecting the significant fraction of plasma membrane-derived proteins partitioning into GPMVs. Lipid and protein diffusion in the PM was, respectively, 2 times and 4–5 times slower in comparison to GPMVs. This discrepancy was quantitatively confirmed by csFCS. The similarity of diffusion of receptors and lipids in GPMVs and GUVs and its significant difference in the plasma membrane suggest that protein domains as small as EGFP convey sensitivity to the actin cortex on various length scales.

Original languageEnglish
Pages (from-to)393-406
Number of pages14
JournalJournal of Membrane Biology
Volume250
Issue number4
DOIs
Publication statusPublished - 1 Aug 2017

Keywords

  • Diffusion coefficient
  • Fluorescence correlation spectroscopy
  • Fluorescent lipid
  • Giant plasma membrane vesicles
  • Giant unilamellar vesicles
  • Interleukin-4 receptor

ASJC Scopus subject areas

  • Biophysics
  • Physiology
  • Cell Biology

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