Fig. 1. Similarities in the lipid composition of rafts and actin cytoskeleton isolated from activated platelets. (A) Cytoskeleton was isolated from platelets (3x10⁹ cells) stimulated or not with 1 IU/ml thrombin for 3 minutes. The major phospholipid and cholesterol composition of isolated cytoskeleton was analyzed as described in the Methods. Results are expressed as the mean±s.d. of three different experiments. Proteins from the isolated cytoskeleton were separated by 7.5% SDS-PAGE and the relative amounts of the raft protein markers CD36 and LAT were analyzed by western blotting. Results shown in the right panel are representative of two independent experiments. (B) Rafts were isolated from 3x10⁹ resting platelets as previously described (Bodin et al., 2003b) and their lipid composition was analyzed. Results are expressed as the mean±s.d. of four different experiments. To illustrate the validity of the raft isolation procedure, the level (% of control) of CD36, a raft marker and ß1 integrin, a transmembrane non-raft protein, in each fraction of the sucrose gradient is represented after quantification of western blots by densitometric analysis (NIH Image). Results shown are the means of two independent experiments.