This Article Full Text Full Text (PDF) All Versions of this Article: biophysj.106.091876v1 92/2/502    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Silva, L. C. Articles by Prieto, M. Search for Related Content PubMed PubMed Citation Articles by Silva, L. C. Articles by Prieto, M.

Ceramide-Domain Formation and Collapse in Lipid Rafts: Membrane Reorganization by an Apoptotic Lipid

Liana C. Silva ^*, Rodrigo F. M. de Almeida ^* , Bruno M. Castro ^*, Alexander Fedorov ^* and Manuel Prieto ^*

^* Centro de Química-Físcia Molecular, Instituto Superior Técnico, Lisbon, Portugal; and Departamento de Química e Bioquímica, Faculdade de Ciências da Universidade de Lisboa, Lisbon, Portugal

Correspondence: Address reprint requests to Liana C. Silva, Centro de Química-Física Molecular, Instituto Superior Técnico, Av. Rovisco Pais, 1049-001 Lisboa, Portugal, Fax: 351-218-464-455; E-mail: lianacsilva{at}ist.utl.pt.

The effect of physiologically relevant ceramide concentrations (4 mol %) in raft model membranes with a lipid composition resembling that of cell membranes, i.e., composed of different molar ratios of an unsaturated glycerophospholipid, sphingomyelin, and cholesterol (Chol) along a liquid-disordered-liquid-ordered tie line was explored. The application of a fluorescence multiprobe and multiparameter approach, together with multiple fluorescence resonance energy transfer (FRET) pairs, in the well-characterized palmitoyl-oleoyl-phosphocholine (POPC)/palmitoyl-sphingomyelin (PSM)/Chol ternary mixture, revealed that low palmitoyl-ceramide (PCer) concentrations strongly changed both the biophysical properties and lipid lateral organization of the ternary mixtures in the low-to-intermediate Chol/PSM-, small raft size range (<25 mol % Chol). For these mixtures, PCer recruited up to three PSM molecules for the formation of very small (4 nm) and highly ordered gel domains, which became surrounded by rafts (liquid-ordered phase) when Chol/PSM content increased. However, the size of these rafts did not change, showing that PCer did not induce the formation of large platforms or the coalescence of small rafts. In the high Chol/PSM-, large raft domains range (>33 mol % Chol), Chol completely abolished the effect of PCer by competing for PSM association. Lipid rafts govern the biophysical properties and lateral organization in these last mixtures.

This article has been cited by other articles:

				J. M. Crane and A. S. Verkman Long-Range Nonanomalous Diffusion of Quantum Dot-Labeled Aquaporin-1 Water Channels in the Cell Plasma Membrane Biophys. J., January 15, 2008; 94(2): 702 - 713. [Abstract] [Full Text] [PDF]

				B. M. Castro, R. F. M. de Almeida, L. C. Silva, A. Fedorov, and M. Prieto Formation of Ceramide/Sphingomyelin Gel Domains in the Presence of an Unsaturated Phospholipid: A Quantitative Multiprobe Approach Biophys. J., September 1, 2007; 93(5): 1639 - 1650. [Abstract] [Full Text] [PDF]

				R. F. M. de Almeida, J. Borst, A. Fedorov, M. Prieto, and A. J. W. G. Visser Complexity of Lipid Domains and Rafts in Giant Unilamellar Vesicles Revealed by Combining Imaging and Microscopic and Macroscopic Time-Resolved Fluorescence Biophys. J., July 15, 2007; 93(2): 539 - 553. [Abstract] [Full Text] [PDF]