Alpha granule

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title: "Alpha granule" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["growth-factors"] description: "Cellular component of platelets" topic_path: "arts/film" source: "https://en.wikipedia.org/wiki/Alpha_granule" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0

::summary Cellular component of platelets ::

::data[format=table title="Infobox anatomy"]

Field	Value
Name	Alpha granule
Latin	granulum alpha
Image	Platelet structure.png
Caption	Alpha granules shown in a platelet
PartOf	Platelets
::

| Name = Alpha granule | Latin = granulum alpha | Image = Platelet structure.png | Caption = Alpha granules shown in a platelet | Image2 = | Caption2 = | Precursor = | System = | Artery = | Vein = | Nerve = | Lymph = | PartOf = Platelets Alpha granules, (α-granules) also known as platelet alpha-granules are a cellular component of platelets. Platelets contain different types of granules that perform different functions, and include alpha granules, dense granules, and lysosomes. Of these, alpha granules are the most common, making up 50% to 80% of the secretory granules. Alpha granules contain several growth factors.

Contents

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

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

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

Clinical significance

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

References

References

1. (July 2009). "Platelet alpha-granules: basic biology and clinical correlates". Blood Reviews.
2. (2015). "Platelet secretory behaviour: as diverse as the granules … or not?". Journal of Thrombosis and Haemostasis.
3. (March 1993). "Platelet alpha-granules". Blood Reviews.
4. (August 2011). "Platelet granules: surprise packages". Blood.
5. (May 2011). "Platelets, inflammation and tissue regeneration". Thrombosis and Haemostasis.
6. (2009). "Nathan and Oski's hematology of infancy and childhood". Elsevier Health Sciences.
7. (2009). "Molecular pathology: the molecular basis of human disease". Academic Press.

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