Thermotropic behavior and lateral distribution of very long chain sphingolipids

A1 Originalartikel i en vetenskaplig tidskrift (referentgranskad)


Interna författare/redaktörer


Publikationens författare: Björkqvist YJE, Brewer J, Bagatolli LA, Slotte JP, Westerlund B
Publiceringsår: 2009
Tidskrift: BBA - Biomembranes
Volym: 1788
Nummer: 6
Artikelns första sida, sidnummer: 1310
Artikelns sista sida, sidnummer: 1320


Abstrakt

Sphingolipids containing very long acyl chains are abundant in certain
specialized tissues and minor components of plasma membranes in most
mammalian cells. There are cellular processes in which these
sphingolipids are required, and the function seems to be mediated
through sphingolipid-rich membrane domains. This study was conducted to
explore how very long acyl chains of sphingolipids influence their
lateral distribution in membranes. Differential scanning calorimetry
showed that 24:0- and 24:1-sphingomyelins, galactosylceramides and
glucosylceramides exhibited complex thermotropic behavior and partial
miscibility with palmitoyl sphingomyelin. The T(m) was decreased by
about 20 degrees C for all 24:1-sphingolipids compared to the
corresponding 24:0-sphingolipids. The ability to pack tightly with
ordered and extended acyl chains is a necessity for membrane lipids to
partition into ordered domains in membranes and thus the
24:1-sphingolipids appeared less likely to do so. Fluorescence quenching
measurements showed that the 24:0-sphingolipids formed ordered domains
in multicomponent membranes, both as the only sphingolipid and mixed
with palmitoyl sphingomyelin. These domains had a high packing density
which appeared to hinder the partitioning of sterols into them, as
reported by the fluorescent cholesterol analog cholestatrienol. 24:0-SM
was, however, better able to accommodate sterol than the
glycosphingolipids. The 24:1-sphingolipids could, depending on head
group structure, either stabilize or disrupt ordered
sphingolipid/cholesterol domains. We conclude that very long chain
sphingolipids, when present in biological membranes, may affect the
physical properties of or the distribution of sterols between lateral
domains. It was also evident that not only the very long acyl chain but
also the specific molecular structure of the sphingolipids was of
importance for their membrane properties.


Senast uppdaterad 2019-15-11 vid 03:25