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Platelet alpha-granule

Alpha granules (or α-granules) are a cellular component of platelets. Platelets contain different types of granules that perform different functions including alpha granules, dense granules, and lysosomes.[1] Of these alpha granules are the most common.[1] The term "alpha granules" is used to describe granules containing several growth factors.[2]

Alpha granule
Part ofPlatelets
Latingranulum alpha
Anatomical terminology


Contents include insulin-like growth factor 1, platelet-derived growth factors, TGFβ, platelet factor 4 (which is a heparin-binding chemokine) and other clotting proteins (such as thrombospondin, fibronectin, factor V,[3] and von Willebrand factor).[4]

The alpha granules express the adhesion molecule P-selectin[5] and CD63.[6] These are transferred to the membrane after synthesis.

The other type of granules within platelets are called dense granules.

Clinical significanceEdit

A deficiency of alpha granules is known as gray platelet syndrome.

See alsoEdit


  1. ^ a b Blair P, Flaumenhaft R (July 2009). "Platelet alpha-granules: basic biology and clinical correlates". Blood Reviews. 23 (4): 177–89. doi:10.1016/j.blre.2009.04.001. PMC 2720568. PMID 19450911.
  2. ^ Harrison P, Cramer EM (March 1993). "Platelet alpha-granules". Blood Reviews. 7 (1): 52–62. doi:10.1016/0268-960X(93)90024-X. PMID 8467233.
  3. ^ Whiteheart SW (August 2011). "Platelet granules: surprise packages". Blood. 118 (5): 1190–1191. doi:10.1182/blood-2011-06-359836. PMID 21816838.
  4. ^ Nurden AT (May 2011). "Platelets, inflammation and tissue regeneration". Thrombosis and Haemostasis. 105 (Suppl 1): S13–33. doi:10.1160/THS10-11-0720. PMID 21479340.
  5. ^ Orkin SH, Nathan DG, Ginsburg D, Look AT (2009). Nathan and Oski's hematology of infancy and childhood. Elsevier Health Sciences. pp. 1386–. ISBN 978-1-4160-3430-8. Retrieved 2 November 2010.
  6. ^ Coleman WB, Tsongalis GJ (2009). Molecular pathology: the molecular basis of human disease. Academic Press. pp. 258–. ISBN 978-0-12-374419-7. Retrieved 2 November 2010.