Covalent modification of platelet proteins by palmitate

L. Muszbek, Michael Laposata

Research output: Contribution to journalArticle

16 Citations (Scopus)

Abstract

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 radiolabelled 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.

Original languageEnglish (US)
Pages (from-to)1339-1347
Number of pages9
JournalBlood
Volume74
Issue number4
StatePublished - 1989
Externally publishedYes

Fingerprint

Palmitates
Platelets
Blood Platelets
Proteins
Fatty Acids
Thrombin
Membranes
Cytoskeleton
Photofluorography
Acylation
Membrane structures
Membrane Glycoproteins
Platelet Activation
Radioactivity
High performance liquid chromatography
Electrophoresis
Amides
Sodium Dodecyl Sulfate

ASJC Scopus subject areas

  • Hematology

Cite this

Covalent modification of platelet proteins by palmitate. / Muszbek, L.; Laposata, Michael.

In: Blood, Vol. 74, No. 4, 1989, p. 1339-1347.

Research output: Contribution to journalArticle

Muszbek, L & Laposata, M 1989, 'Covalent modification of platelet proteins by palmitate', Blood, vol. 74, no. 4, pp. 1339-1347.
Muszbek, L. ; Laposata, Michael. / Covalent modification of platelet proteins by palmitate. In: Blood. 1989 ; Vol. 74, No. 4. pp. 1339-1347.
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