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Covalent modification of platelet proteins by palmitate
1Department of Pathology and Laboratory Medicine, University of Pennsylvania, School of Medicine, Philadelphia 19104.
Blood
|September 1, 1989
Summary
Platelet proteins are modified with fatty acids, particularly palmitate, and these proteins associate with the cytoskeleton upon thrombin stimulation. This palmitoylation is a key response to platelet activation.
Area of Science:
- Biochemistry
- Cell Biology
- Hematology
Background:
- Fatty acid acylation is crucial for protein association with cell membranes.
- Platelet membrane glycoproteins have been studied, but fatty acid modification of platelet proteins remains largely unexamined.
Purpose of the Study:
- To investigate if platelet proteins undergo fatty acid acylation.
- To determine the location of these modified proteins within platelet fractions.
- To assess changes in fatty acid acylated proteins following thrombin stimulation.
Main Methods:
- Incorporation of radiolabeled palmitate (3H-palmitate) into platelets.
- Analysis of fatty acid linkages (thioester, O-ester, amide) using High-Performance Liquid Chromatography (HPLC).
- Detection of radiolabeled proteins via Sodium Dodecyl Sulfate-Polyacrylamide Gel Electrophoresis (SDS-PAGE) and fluorography.
Main Results:
- A small percentage (1.37%) of incorporated radioactivity was covalently bound to platelet proteins, primarily as thioester-linked 3H-palmitate.
- At least ten major radiolabeled proteins were identified.
- Thrombin stimulation significantly increased the association of 3H-palmitoylated proteins with the platelet cytoskeleton.
- Most palmitoylated proteins were found in the membrane fraction, suggesting integral or peripheral membrane localization.
- The GPIIb-IIIa complex components were not found to be palmitoylated.
Conclusions:
- Platelet proteins undergo significant post-translational modification via palmitoylation.
- The incorporation of palmitoylated proteins into the cytoskeleton is a major component of the platelet response to thrombin.
- This study provides novel insights into the functional roles of protein lipidation in platelet activation and membrane dynamics.
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