Table 3.
Platelet surface glycoproteins (GP's) and agonists
| Major Platelet Glycoprotein (GP) Receptors | |||
|---|---|---|---|
| Classical | CD # | Integrin | Activating Ligand(s) |
| GP IIb/IIIa | CD41b | αIIbß3. | 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 | αVß3. | 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 αVß1), 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].