Biosynthesis of major platelet proteins in human blood platelets

Authors

  • Nelly KIEFFER,

    Corresponding author
    1. Institut National de la Santé et de la Recherche Médicale, Unité 91, Hôpital Henri Mondor, Créteil
      Correspondence to N. Kieffer Institut National de la Santé et de la Recherche Médicale, Unité 91, Hôpital Henri Mondor, 51, Avenue du Maréchal de Lattre de Tassigny, F-94010 Créteil, France
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  • Josette GUICHARD,

    1. Institut National de la Santé et de la Recherche Médicale, Unité 91, Hôpital Henri Mondor, Créteil
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  • Jean-Pierre FARCET,

    1. Institut National de la Santé et de la Recherche Médicale, Unité 91, Hôpital Henri Mondor, Créteil
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  • William VAINCHENKER,

    1. Institut National de la Santé et de la Recherche Médicale, Unité 91, Hôpital Henri Mondor, Créteil
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  • Janine BRETON-GORIUS

    1. Institut National de la Santé et de la Recherche Médicale, Unité 91, Hôpital Henri Mondor, Créteil
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Correspondence to N. Kieffer Institut National de la Santé et de la Recherche Médicale, Unité 91, Hôpital Henri Mondor, 51, Avenue du Maréchal de Lattre de Tassigny, F-94010 Créteil, France

Abstract

We studied de novo protein biosynthesis in platelets of normal adult donors and in newly formed platelets isolated from splenectomized patients with idiopathic thrombocytopenic purpura (ITP). After metabolic labelling of platelet proteins, performed with different radiolabelled amino acids or carbohydrates, a tenfold increase in incorporation of radioactivity into trichloroacetic-acid-precipitable material was obtained with ITP platelets compared to control platelets. Electron microscopic studies of ITP platelets revealed the presence of rough endoplasmic reticulum and polyribosomes, providing morphological evidence for protein synthesis. SDS-PAGE of radiolabelled ITP platelet proteins followed by autoradiography showed that [35S]methionine and [3H]leucine were incorporated into almost all Coomassie-blue-stained proteins whereas [3H]carbohydrates only labelled a few bands. Using crossed-immunoelectrophoresis we identified some of the labelled platelet compounds and demonstrated that major membrane glycoproteins (GPIb, IIb, IIIa) and alpha-granule proteins, such as fibrinogen, thrombospondin, albumin and von Willebrand factor, were synthesized in newly formed circulating platelets.

Abbreviations
ITP

idiopathic thrombocytopenic purpura

GP

glycoprotein

PF4

platelet factor 4

NaCl/Pi

phosphate-buffered saline

Me2SO

dimethylsulfoxide