Rap2, but not Rap1 GTPase is expressed in human red blood cells and is involved in vesiculation

Fabio Greco, Annarita Ciana, Daniela Pietra, Cesare Balduini, Giampaolo Minetti, Mauro Torti

Research output: Contribution to journalArticlepeer-review


Recent studies have suggested that Rap1 and Rap2 small GTP-binding proteins are both expressed in human red blood cells (RBCs). In this work, we carefully examined the expression of Rap proteins in leukocytes- and platelets-depleted RBCs, whose purity was established on the basis of the selective expression of the β2 subunit of the Na+/K+-ATPase, as verified according to the recently proposed "β-profiling test" [J.F. Hoffman, A. Wickrema, O. Potapova, M. Milanick, D.R. Yingst, Na pump isoforms in human erythroid progenitor cells and mature erythrocytes, Proc. Natl. Acad. Sci. U. S. A. 99 (2002) 14572-14577]. In pure RBCs preparations, Rap2, but not Rap1 was detected immunologically. RT-PCR analysis of mRNA extracted from highly purified reticulocytes confirmed the expression of Rap2b, but not Rap2a, Rap2c, Rap1a or Rap1b. In RBCs, Rap2 was membrane-associated and was rapidly activated upon treatment with Ca2+/Ca2+-ionophore. In addition, Rap2 segregated and was selectively enriched into microvesicles released by Ca2+-activated RBCs, suggesting a possible role for this GTPase in membrane shedding.

Original languageEnglish
Pages (from-to)330-335
Number of pages6
JournalBiochimica et Biophysica Acta - Molecular Cell Research
Issue number3
Publication statusPublished - Mar 2006


  • Rap1
  • Rap2
  • Red blood cells
  • Small GTPases
  • Vesiculation

ASJC Scopus subject areas

  • Cell Biology
  • Molecular Biology
  • Biophysics


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