Thrombospondin binds normally to glycoprotein IIIb deficient platelets

Glycoprotein IIIb (GPIV, CD36) has been proposed as the platelet receptor for thrombospondin (TSP). We found two healthy blood donors, whose platelets were shown to be GPIIIb deficient. These platelets expressed endogeneous TSP as control platelets and their binding capacity for exogeneous TSP was the same. These results indicate that GPIIIb is not the major TSP receptor on platelets. However, it is not yet possible to exclude that in GPIIIb-deficient platelets other proteins may substitute for GPIIIb in TSP binding.