P. Dobner et al., Platelet high affinity low density lipoprotein binding and import of lipoprotein derived phospholipids, FEBS LETTER, 444(2-3), 1999, pp. 270-274
The binding of low density lipoprotein (LDL) to the platelet cell membrane
could facilitate the transfer of phospholipids from LDL to the platelets. A
polyclonal antibody against the platelet glycoproteins IIb/IIIa inhibited
the high affinity binding of I-125-LDL by up to 80%. The transfer of pyrene
(py)-labeled sphingomyelin (SM), phosphatidylcholine and phosphatidylethan
olamine from LDL to the platelets was unaffected by the antibody. The lecti
n wheat germ agglutinin (WGA) reduced the binding of I-125-LDL to the plate
lets by approximately 80%. In contrast, the lectin stimulated the transfer
of SM from LDL into the platelets ba about three-fold. WGA also specificall
y augmented the transfer of py-SM between lipid vesicles and the platelets,
the stimulation being abolished in the presence of N-acetylglucosamine, De
xtran sulfate (DS) increased the specific binding of I-125-LDL to the plate
lets by up to 2.8-fold. On the other hand, the import of LBL-derived py-pho
spholipids was unaffected by DS. Together, the results indicate that the ph
ospholipid transfer from LDL to the platelets is independent of the high af
finity LDL binding to the platelets and is specifically stimulated by WGA.
Thus, the interactions of platelets with LDL phospholipids differ markedly
from those with the apoprotein components of the lipoproteins. (C) 1999 Fed
eration of European Biochemical Societies.