What are alpha granules?

Alpha granules contain a plethora of proteins that comprise the bulk of the platelet secretome, including hemostatic factors (eg, Factor V, VWF, fibrinogen), angiogenic factors (eg, angiogenin, VEGF), anti-angiogenic factors (eg, angiostatin, PF4), growth factors (eg, PDGF, bFGF, SDF1α), proteases (eg, MMP2, MMP9).

What are the granules found in platelets?

Platelets contain at least three major types of granules— α-granules, dense granules, and lysosomes—which carry distinct cargos and vary in biogenesis, trafficking, and exocytosis.

Why platelets have granules?

Dense granules play a critical role in hemostasis and thrombosis, releasing factors such as ADP and epinephrine that act in an autocrine and paracrine manner to stimulate platelets at sites of vascular injury. Dense granules also contain factors that are vasoconstrictive such as serotonin (Flaumenhaft, 2013).

What do dense granules of platelets release?

platelet function For example, dense granules contain large quantities of calcium ions and adenosine diphosphate (ADP). Upon release from the platelet, ADP stimulates other platelets…

What are the different types of alpha granules?

…types of internal granules: the alpha granules, the dense granules, and the lysosomes. Each of these granules is rich in certain chemicals that have an important role in platelet function. For example, dense granules contain large quantities of calcium ions and adenosine diphosphate (ADP). Upon release from the platelet, ADP…

How are alpha granules transferred to the membrane?

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.

What kind of granules are found in a platelet?

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 between 50% to 80% of the secretory granules. Alpha granules contain several growth factors.

Where does the development of α granules begin?

The development of α–granules begins in the megakaryocyte, but continues in the circulating platelet.