Fig. 6. Lipid raft association of the GPI-anchored constructs. (A-F) MDCK cells stably expressing either wtMDP or MDPgly were lysed in MBS containing 0.5% Lubrol WX at 4°C and lipid rafts isolated by buoyant sucrose density gradient centrifugation. The sucrose gradients were fractionated in 0.5 ml aliquots (P, insoluble pellet; 1, bottom of tube; 9 top of tube). Total protein in each fraction was measured (A) and activity assays for dipeptidyl peptidase IV (D) and MDP (F) were carried out. Fractions were also analysed by immunoblotting with (B) caveolin-1, (C) clathrin or (E) MDP. The results are representative of three experiments.