C. Dietrich et al., Partitioning of Thy-1, GM1, and cross-linked phospholipid analogs into lipid rafts reconstituted in supported model membrane monolayers, P NAS US, 98(19), 2001, pp. 10642-10647
Citations number
52
Categorie Soggetti
Multidisciplinary
Journal title
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
As shown earlier, raft-like domains resembling those thought to be present
in natural cell membranes can be formed in supported planar lipid monolayer
s. These liquid-ordered domains coexist with a liquid-disordered phase and
form in monolayers prepared both from synthetic lipid mixtures and lipid ex
tracts of the brush border membrane of mouse kidney cells. The domains are
detergent-resistant and are highly enriched in the glycosphingolipid GM1. I
n this work, the properties of these raft-like domains are further explored
and compared with properties thought to be central to raft function in pla
sma membranes. First, it is shown that domain formation and disruption crit
ically depends on the cholesterol density and can be controlled reversibly
by treating the monolayers with the cholesterol-sequestering reagent methyl
-beta -cyclodextrin. Second, the glycosylphosphatidylinositol-anchored cell
-surface protein Thy-1 significantly partitions into the raft-like domains.
The extent of this partitioning is reduced when the monolayers contain GM1
, indicating that different molecules can compete for domain occupation. Th
ird, the partitioning of a saturated phospholipid analog into the raft phas
e is dramatically increased (15% to 65%) after cross-linking with antibodie
s, whereas the distribution of a doubly unsaturated phospholipid analog is
not significantly affected by cross-linking (approximate to 10%). This resu
lt demonstrates that cross-linking, a process known to be important for cer
tain cell-signaling processes, can selectively translocate molecules to liq
uid-ordered domains.