N-palmitoyl-sulfatide participates in lateral domain formation in complex lipid bilayers

A1 Journal article (refereed)


Internal Authors/Editors


Publication Details

List of Authors: Björkqvist YJE, Nybond S, Nyholm TKM, Slotte JP, Ramstedt B
Publication year: 2008
Journal: BBA - Biomembranes
Volume number: 1778
Issue number: 4
Start page: 954
End page: 962


Abstract

Sulfatides (galactosylceramidesulfates) are negatively charged
glycosphingolipids that are important constituents of brain myelin
membranes. These membranes are also highly enriched in
galactosylceramide and cholesterol. It has been implicated that
sulfatides, together with other sphingolipids, take part in lateral
domain formation in biological membranes. This study was conducted to
characterize the lateral phase behavior of N-palmitoyl-sulfatide in
mixed bilayer membranes. Going from simple lipid mixtures with sulfatide
as the only sphingolipid in a fluid matrix of POPC, to more complex
membranes including other sphingolipids, we have examined 1) ordered
domain formation with sulfatide, 2) sterol enrichment in such domains
and 3) stabilization of the domains against temperature by the addition
of calcium. Using two distinct phase selective fluorescent probes,
trans-parinaric acid and cholestatrienol, together with a quencher in
the fluid phase, we were able to distinguish between ordered domains in
general and ordered domains enriched in sterol. We found that
N-palmitoyl-sulfatide formed ordered domains when present as the only
sphingolipid in a fluid phospholipid bilayer, but these domains did not
contain sterol and their stability was unaffected by calcium. However,
at low, physiologically relevant concentrations, sulfatide partitioned
favorably into domains enriched in other sphingolipids and cholesterol.
These domains were stabilized against temperature in the presence of
divalent cations. We conclude that sulfatides are likely to affect the
lateral organization of biomembranes.


Last updated on 2019-19-07 at 05:57