This Article Full Text Full Text (PDF) All Versions of this Article: biophysj.104.057059v1 88/4/2670    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 Malewicz, B. Articles by Brown, R. E. Search for Related Content PubMed PubMed Citation Articles by Malewicz, B. Articles by Brown, R. E.

The 3-Hydroxy Group and 4,5-trans Double Bond of Sphingomyelin Are Essential for Modulation of Galactosylceramide Transmembrane Asymmetry

Barbara Malewicz ^*, Jacob T. Valiyaveettil , Kochurani Jacob , Hoe-Sup Byun , Peter Mattjus ^*, Wolfgang J. Baumann ^*, Robert Bittman  and Rhoderick E. Brown ^*

^* University of Minnesota, Hormel Institute, Austin, Minnesota 55912; and Department of Chemistry and Biochemistry, Queens College of the City University of New York, Flushing, New York 11367

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

The structural features of SPM that control the transbilayer distribution of ß-GalCer in POPC vesicles were investigated by ¹³C- and ³¹P-NMR spectroscopy using lipid analogs that share physical similarities with GalCer or SPM. The SPM analogs included N-palmitoyl-4,5-dihydro-SPM, 3-deoxy-SPM, 1-alkyl-2-amidophosphatidylcholine, and dipalmitoylphosphatidylcholine, a popular model "raft lipid". The transbilayer distributions of the SPM analogs and SPM in POPC vesicles were similar by ³¹P-NMR. To observe the dramatic change in GalCer transbilayer distribution that occurs when SPM is included in POPC vesicles, the 3-OH group, 4,5-trans double bond, and amide linkage all were required in SPM. However, inclusion of 2 and 10 mol % dihydroSPM in SPM/POPC (1:1) vesicles mitigated and completely abrogated the effect of SPM on the transbilayer distribution of GalCer. Despite sharing some structural features with GalCer and localizing preferentially to the inner leaflet of POPC vesicles, dimyristoylphosphatidylethanolamine did not undergo a change in transbilayer distribution when SPM was incorporated into the vesicles. The results support the hypothesis that specific interactions may be favored among select sphingolipids in curvature-stressed membranes and emphasize the potential importance of the SPM-dihydroSPM ratio in membrane fission and fusion processes associated with vesicle biogenesis and trafficking.

This article has been cited by other articles:

				C. D. Blanchette, W.-C. Lin, T. V. Ratto, and M. L. Longo Galactosylceramide Domain Microstructure: Impact of Cholesterol and Nucleation/Growth Conditions Biophys. J., June 15, 2006; 90(12): 4466 - 4478. [Abstract] [Full Text] [PDF]