Analysis by cosedimentation of the interaction between the C1q GR and PS-containing liposomes. The C1q GR was allowed to interact with liposomes containing PS, PC, phosphatidylethanolamine, or a 1:1 PC:PS mixture. After ultracentrifugation, the pellet and supernatant fractions were separated and their relative GR content was assessed by SDS-PAGE analysis as described in Materials and Methods. Molecular mass markers are indicated on the right. P, Pellet; S, supernatant. The data shown are representative of three independent experiments.