Role of platelets in neuroinflammation: a wide-angle perspective

Table 3 Platelet surface glycoproteins (GP's) and agonists

		Major Platelet Glycoprotein (GP) Receptors
Classical	CD #	Integrin	Activating Ligand(s)
GP IIb/IIIa	CD41b	α_IIbß₃.	Fibrinogen, vWF, fibronectin, vitronectin
GP Ib-IX	CD42a,b,c		vWF, thrombin
GP Ia-IIa	CD49b	α₂ß₁.	Collagen
GP Ic-IIa	CD49e	α₅ß₁.	Fibronectin
GP Ic-IIa	CD49f	α₆ß₁.	Laminin
Vitronectin		α_Vß₃.	Vitronectin, vWF, fibronectin, fibrinogen, TSP
PECAM-1	CD31		Further interaction with endothelium
P-selectin*	CD62P		Interaction with leukocytes
* a.k.a. PADGEM or GMP-140 in the older literature.
Listed: Ib, IIa, IIb, IIIa, IIIb (a.k.a. GP IV, CD36), V, IX.

The classical GP designations (which are based on location in electrophoresis) are given in the first column and the antigen CD numbers in the 2nd column. The 3rd column gives the newer integrin names, which are compounded of two subunit types (α, ß). Integrin nomenclature is awkward, hence the classical names remain in wide use. Many of the GP's are known also by other names, e.g. VLA-2, -3, -5, -6 (for "very late antigens") corresponding respectively to integrins α₂ß₁, α₃ß₁, α₅ß₁ (or α_Vß₁), and α₆ß₁. The 4th and last column gives the ligands which activate platelets via those GP receptors, and if more than 1 is given, they are in order of potency. For example, the complex GP Ib-IX is the main site for vWF but it has some activity for other GP sites, and likewise collagen. In most cases there is evidence of receptor mobility, clustering, interaction, synergy and inter-dependence, as noted for Table 4. Data adapted from Table 22.1 and others in Colman et al [10].

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