Lipid domain morphologies in phosphatidylcholine−ceramide monolayers

M.E.J. Karttunen, M. Haataja, V.M.J. Säily, I. Vattulainen, J.M. Holopainen

    Research output: Contribution to journalArticleAcademicpeer-review

    26 Citations (Scopus)

    Abstract

    In cells, one of the main roles of ceramide-enriched membrane domains is to recruit or exclude intracellular signaling molecules and receptors, thereby facilitating signal transduction cascades. Accordingly, in model membranes, even low contents of ceramide segregate into lateral domains. The impact of the N-acyl chain on this segregation and on the morphology of the domains remains to be explored. Using Langmuir monolayers, we have systematically studied binary mixtures of 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) and ceramide (2:1, molar ratio) and varied the N-acyl chain length of ceramide from 2 to 24 carbon atoms (Cer2 to Cer24). Fluid Cer2, Cer6, and Cer8/DMPC mixtures were miscible at all surface pressures. Longer ceramides, however, formed surface pressure-dependent immiscible mixtures with DMPC. The domain morphology under fluorescence microscopy after including a trace amount of fluorescent NBD-phosphatidylcholine into DMPC/Cer mixtures was found to be very sensitive to the N-acyl chain length. Shorter ceramides (Cer10-Cer14) formed flower-like (seaweed) domains, whereas longer ceramides (N-acyl chain length >14 carbon atoms) formed round and regular domains. We attribute the formation of the flower patterns to diffusive morphological instabilities during domain growth.
    Original languageEnglish
    Pages (from-to)4595-4600
    JournalLangmuir
    Volume25
    Issue number8
    DOIs
    Publication statusPublished - 2009

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