This Article Full Text Full Text (PDF) All Versions of this Article: biophysj.106.084921v1 91/7/2490    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 Zhai, X. Articles by Brown, R. E. Search for Related Content PubMed PubMed Citation Articles by Zhai, X. Articles by Brown, R. E.

Lactosylceramide: Lateral Interactions with Cholesterol

University of Minnesota, Hormel Institute, Austin, Minnesota

Correspondence: Address reprint requests to Rhoderick E. Brown, E-mail: rebrown{at}hi.umn.edu or reb{at}umn.edu.

Lactosylceramide (LacCer) is a key intermediate in glycosphingolipid metabolism and is highly enriched in detergent-resistant biomembrane fractions associated with microdomains, i.e., rafts and caveolae. Here, the lateral interactions of cholesterol with LacCers containing various homogeneous saturated (8:0, 16:0, 18:0, 24:0) or monounsaturated acyl chains (18:1, 24:1) have been characterized using a Langmuir-type film balance. Cholesterol-induced changes in lateral packing were assessed by measuring changes in average molecular area, i.e., area condensations, and in lateral elasticity, i.e., surface compressional moduli () with emphasis on high surface pressures (30 mN/m) that mimic biomembrane conditions. Cholesterol most dramatically affected the lateral packing elasticity of LacCers with long saturated acyl chains at sterol mole fractions 0.3, consistent with liquid-ordered (LO) phase formation. The lateral elasticity within the LacCer-cholesterol LO-phase was much lower than that observed within pure LacCer condensed, i.e., gel, phase. The magnitude of the cholesterol-induced reduction in lateral elasticity was strongly mitigated by cis monounsaturation in the LacCer acyl chain. At identical high sterol mole fractions, higher lateral elasticity was observed within LacCer-cholesterol mixtures compared with galactosylceramide-cholesterol and sphingomyelin-cholesterol mixtures. The results show how changes to sphingolipid headgroup and acyl chain structure contribute to the modulation of lateral packing elasticity in sphingolipid-cholesterol LO-phases.

This article has been cited by other articles:

				W.-C. Lin, C. D. Blanchette, and M. L. Longo Fluid-Phase Chain Unsaturation Controlling Domain Microstructure and Phase in Ternary Lipid Bilayers Containing GalCer and Cholesterol Biophys. J., April 15, 2007; 92(8): 2831 - 2841. [Abstract] [Full Text] [PDF]