In platelets, the term "alpha granules" is used to describe granules containing several growth factors (such as insulin-like growth factor 1, platelet-derived growth factor, TGFβ), platelet factor 4 which is a heparin-binding chemokine, and other clotting proteins (such as thrombospondin and fibronectin.) The alpha granules express the adhesion molecule P-selectin. The other type of granules within platelets are called dense granules.
A deficiency of alpha granules is known as grey platelet syndrome.
Summary -- alpha granules contain: - plt factor 4 - PDGF - fibronectin - beta-thromboglobulin - vWF - factor V - factor XIII - fibrinogen
- Harrison P, Cramer E (1993). "Platelet alpha-granules". Blood Rev. 7 (1): 52–62. PMID 8467233.