Role of ceramide in membrane protein organization investigated by combined AFM and FCS

Biochim Biophys Acta. 2008 May;1778(5):1356-64. doi: 10.1016/j.bbamem.2008.02.008. Epub 2008 Feb 29.

Abstract

Ceramide-induced alterations in the lateral organization of membrane proteins can be involved in several biological contexts, ranging from apoptosis to viral infections. In order to investigate such alterations in a simple model, we used a combined approach of atomic force microscopy, scanning fluorescence correlation spectroscopy and confocal fluorescence imaging to study the partitioning of different membrane components in sphingomyelin/dioleoyl-phosphatidylcholine/cholesterol/ceramide supported bilayers. Such model membranes exhibit coexistence of liquid-disordered, liquid-ordered (raft-like) and ceramide-rich lipid phases. Our results show that components with poor affinity toward the liquid-ordered phase, such as several fluorescent lipid analogues or the synaptic protein Synaptobrevin 2, are excluded from ceramide-rich domains. Conversely, we show for the first time that the raft-associated protein placental alkaline phosphatase (GPI-PLAP) and the ganglioside GM1 are enriched in such domains, while exhibiting a strong decrease in lateral diffusion. Analogue modulation of the local concentration and dynamics of membrane proteins/receptors by ceramide can be of crucial importance for the biological functions of cell membranes.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alkaline Phosphatase / metabolism
  • Ceramides / physiology*
  • Diffusion
  • Glycosylphosphatidylinositols / metabolism
  • Membrane Proteins / chemistry
  • Membrane Proteins / metabolism*
  • Microscopy, Atomic Force / methods*
  • Spectrometry, Fluorescence / methods*

Substances

  • Ceramides
  • Glycosylphosphatidylinositols
  • Membrane Proteins
  • Alkaline Phosphatase