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

CHIANTIA, S.; RIES, J.; CHWASTEK, G.; CARRER, D. C.; LI, Z.; BITTMAN, R.; SCHWILLE, P.

BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES

Elsevier

Lugar: Amsterdam; Año: 2008 vol. 1778 p. 1356 - 1364

0005-2736

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 forcemicroscopy, scanning fluorescence correlation spectroscopy and confocal fluorescence imaging to study the partitioning of differentmembrane 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 synapticprotein Synaptobrevin 2, are excludedfromceramide-rich domains. Conversely,we showfor 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.