Covalent binding of arachidonate to G protein α subunits of human platelets

Hazem Hallak, Laszlo Muszbek, Michael Laposata, Elizabeth Belmonte, Lawrence F. Brass, David R. Manning

Research output: Contribution to journalArticle

88 Citations (Scopus)

Abstract

The α subunits of GTP-binding regulatory proteins (G proteins) are subject to lipid modifications required for anchorage to membrane and/or interactions with other proteins. With the knowledge that α subunits are palmitoylated, which we demonstrate here for human platelets, we sought to determine whether these subunits also bind arachidonate and myristate in a covalent, post-translational manner. All α subunits examined were found to incorporate radioactivity upon incubation of human platelets with [3H]palmitate, [3H]arachidonate, and [3H]myristate. The identity of [3H]palmitate and [3H]arachidonate as covalently bound fatty acids was confirmed by high pressure liquid chromatography following alkaline methanolysis. With [3H]myristate, however, the bound fatty acid proved to be [3H]palmitate, presumably generated by a 2-carbon chain elongation. Protein- bound [3H]palmitate and [3H]arachidonate were released by hydroxylamine at neutral pH, implying a thioester linkage between protein and fatty acid. Thus, post-translational modifications of G protein α subunits include palmitoylation and arachidonoylation, but not myristoylation. Given the different physical properties of saturated and unsaturated fatty acids and the large-scale release of arachidonate during platelet activation, changes in arachidonate incorporation may serve as an important regulator of α subunit function.

Original languageEnglish (US)
Pages (from-to)4713-4716
Number of pages4
JournalJournal of Biological Chemistry
Volume269
Issue number7
StatePublished - Feb 18 1994
Externally publishedYes

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Palmitates
Protein Subunits
Platelets
Guanosine Triphosphate
GTP-Binding Proteins
Myristic Acid
Fatty Acids
Blood Platelets
Proteins
High pressure liquid chromatography
Lipoylation
Hydroxylamine
Platelet Activation
Radioactivity
Post Translational Protein Processing
Unsaturated Fatty Acids
Elongation
Carbon
Physical properties
Chemical activation

ASJC Scopus subject areas

  • Biochemistry

Cite this

Hallak, H., Muszbek, L., Laposata, M., Belmonte, E., Brass, L. F., & Manning, D. R. (1994). Covalent binding of arachidonate to G protein α subunits of human platelets. Journal of Biological Chemistry, 269(7), 4713-4716.

Covalent binding of arachidonate to G protein α subunits of human platelets. / Hallak, Hazem; Muszbek, Laszlo; Laposata, Michael; Belmonte, Elizabeth; Brass, Lawrence F.; Manning, David R.

In: Journal of Biological Chemistry, Vol. 269, No. 7, 18.02.1994, p. 4713-4716.

Research output: Contribution to journalArticle

Hallak, H, Muszbek, L, Laposata, M, Belmonte, E, Brass, LF & Manning, DR 1994, 'Covalent binding of arachidonate to G protein α subunits of human platelets', Journal of Biological Chemistry, vol. 269, no. 7, pp. 4713-4716.
Hallak H, Muszbek L, Laposata M, Belmonte E, Brass LF, Manning DR. Covalent binding of arachidonate to G protein α subunits of human platelets. Journal of Biological Chemistry. 1994 Feb 18;269(7):4713-4716.
Hallak, Hazem ; Muszbek, Laszlo ; Laposata, Michael ; Belmonte, Elizabeth ; Brass, Lawrence F. ; Manning, David R. / Covalent binding of arachidonate to G protein α subunits of human platelets. In: Journal of Biological Chemistry. 1994 ; Vol. 269, No. 7. pp. 4713-4716.
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