Detergent-resistant cytoskeleton of the surface-activated platelet differs
from the suspension-activated platelet cytoskeleton
CM Smith , SM Burris, GH Rao and JG White
Department of Pediatrics, University of Minnesota Health Sciences Center,
Minneapolis 55455.
This study contrasts the protein composition of the detergent-resistant
cytoskeleton of platelets fully spread on glass with the cytoskeletal
composition of resting platelets and platelets aggregated in suspension
with thrombin. Complete Triton X-100-insoluble cytoskeletons were isolated
from spread, resting, and suspension-activated platelets in the presence of
protease inhibitors, solubilized in sodium dodecyl sulfate/EDTA and
analyzed on reduced, one-dimensional polyacrylamide gels. The protein
composition of the cytoskeletons differed both qualitatively and
quantitatively. Most notable were more extensive incorporation of total
protein, talin, and vinculin into the cytoskeleton of spread platelets than
the cytoskeleton of suspension- activated platelets. Varying the
concentration and time of exposure to thrombin during suspension activation
did not mimic the cytoskeletal changes of surface activation. Scanning
electron microscopy, measurement of lipid phosphorus content, and varying
the duration of Triton extraction did not show incomplete solubilization or
nonspecific trapping of constituents in the spread platelet cytoskeleton.
Proteolysis of talin was minimal in suspension-activated platelets and in
platelets spread for 50 minutes. The differences in the detergent-
resistant cytoskeletons of surface- and suspension-activated platelets
indicate significant divergence in the physiologies of platelet spreading
on surfaces and platelet activation in suspension.
Volume 80,
Issue 11,
pp. 2774-2780,
12/01/1992
Copyright © 1992 by The American Society of Hematology
