CD36 is spatially associated with glycoprotein IIb-IIIa (alpha IIb beta 3) on the surface of resting platelets

Platelet activation and aggregation induced by agonists such as thrombin are accompanied by the phosphorylation of several proteins on tyrosine. Such tyrosine phosphorylation is dependent upon activation and ligand engagement of the major integrin receptor on the surface of platelets, glycoprotein (GP) IIb-IIIa (alpha IIb beta 3), but how this is accomplished is not known. The only platelet membrane GP known to associate with non receptor tyrosine kinases is CD36 (GPIV) which forms associations with pp60(Fyn), pp62(Yes), and pp54/58(Lyn), and antibodies directed against CD36 activate platelets in a process dependent upon GPIIb-IIIa. These and other data suggest physical association between the two membrane GPs, IIb-IIIa and CD36. By the use of immunoprecipitation of lysates of platelets that have been surface labeled and chemically crosslinked we show here that CD36 and GPIIb-IIIa are spatially associated on the surface of resting platelets. (C) 1996 Academic Press, Inc.