Covalent modification of platelet proteins by palmitate
- Univ. of Pennsylvania, Philadelphia (USA)
Covalent attachment of fatty acid to proteins plays an important role in association of certain proteins with hydrophobic membrane structures. In platelets, the structure of many membrane glycoproteins (GPs) has been examined in detail, but the question of fatty acid acylation of platelet proteins has not been addressed. In this study, we wished to determine (a) whether platelet proteins could be fatty acid acylated; and, if so, (b) whether these modified proteins were present in isolated platelet membranes and cytoskeletal fractions; and (c) if the pattern of fatty acid acylated proteins changed on stimulation of the platelets with the agonist thrombin. We observed that in platelets allowed to incorporate 3H-palmitate, a small percentage (1.37%) of radioactivity incorporated into the cells became covalently bound to protein. Selective cleavage of thioester, thioester plus O-ester, and amide-linked 3H-fatty acids from proteins, and their subsequent analysis by high-performance liquid chromatography (HPLC) indicated that the greatest part of 3H-fatty acid covalently bound to protein was thioester-linked 3H-palmitate. By sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and fluorography, at least ten major radiolabeled proteins were detected. Activation of platelets by thrombin greatly increased the quantity of 3H-palmitoylated proteins associated with the cytoskeleton. Nearly all radiolabeled proteins were recovered in the membrane fraction, indicating that these proteins are either integral or peripheral membrane proteins or proteins tightly associated to membrane constituents. Components of the GPIIb-IIIa complex were not palmitoylated. Thus, platelet proteins are significantly modified posttranslationally by 3H-palmitate, and incorporation of palmitoylated proteins into the cytoskeleton is a prominent component of the platelet response to thrombin stimulation.
- OSTI ID:
- 5162732
- Journal Information:
- Blood; (USA), Vol. 74:4; ISSN 0006-4971
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
HEXADECANOIC ACID
BIOLOGICAL FUNCTIONS
MEMBRANE PROTEINS
POST-TRANSLATION MODIFICATION
ACYLATION
BLOOD PLATELETS
CELL MEMBRANES
ELECTROPHORESIS
GLYCOPROTEINS
HYDROCHLORIC ACID
HYDROLYSIS
HYDROXYLAMINE
LIQUID COLUMN CHROMATOGRAPHY
MOLECULAR WEIGHT
TRACER TECHNIQUES
TRITIUM COMPOUNDS
AMINES
BIOLOGICAL MATERIALS
BLOOD
BLOOD CELLS
BODY FLUIDS
CARBOXYLIC ACIDS
CELL CONSTITUENTS
CHEMICAL REACTIONS
CHROMATOGRAPHY
DECOMPOSITION
FUNCTIONS
HYDROGEN COMPOUNDS
INORGANIC ACIDS
ISOTOPE APPLICATIONS
LYSIS
MATERIALS
MEMBRANES
MONOCARBOXYLIC ACIDS
ORGANIC ACIDS
ORGANIC COMPOUNDS
PROTEINS
SEPARATION PROCESSES
SOLVOLYSIS
550200* - Biochemistry