[Importance of the interaction of surface receptors with the cytoskeleton for platelet function]

Two Triton-X-100-insoluble cytoskeletal fractions were prepared from washed human blood platelets by centrifugation: a low speed sediment (TP) and a fraction recovered as ultracentrifugation pellet (UP). Glycoproteins associated with both fractions prior to and after different times of thrombin activation were analyzed by electrophoretic techniques. In the TP fraction of unstimulated platelet the major membrane glycoproteins (GP) Ib and Ia were detected. After thrombin stimulation there is a rapid increase of GPs Ia, Ib, IIIb and a Mr 250,000-GP and a slower appearance of GPs IIb and IIIa in this fraction. The UP fraction contains mainly GPs Ib, Ia, IIb, IIIa and a Mr 250,000-GP. Thrombin activation does not cause any significant changes in the glycopeptide pattern of this fraction.