Lipoprotein electrophoresis of apoE-VLDL particles. Various apoE proteins were incubated with apoE(-) mice serum at 37°C for 4 h, respectively. After removing the free proteins by NaBr density ultracentrifugation, the VLDL particles were checked by zone electrophoresis (separation by charge). Lanes 1 and 5, human serum sample; lane 2 and 6, apoE(-) mice serum sample; lane 3-4 and 7-9, apoE(-) mice serum incubated with full length apoE3 and apoE4, and with apoE2-, apoE3-, and apoE4-(72-166) proteins, respectively. The VLDL bands were shifted with the binding of apoE proteins. Detailed procedures are described in Materials and Methods.