Figure 6.

SLMV formation in PC12 cells expressing rab4, Q67Lrab4, and S22Nrab4. Cells were labeled with ¹²⁵I-Cl 604.1 mAb against synaptotagmin for 40 min at 15°C, washed, and reincubated with fresh medium for 15 min at 37°C or at 0°C. SLMVs were isolated on glycerol velocity gradients. A single peak of labeled SLMVs appeared in fraction 8–10 that is not affected in cells expressing rab4 (▴) as compared with control cells (♦). In contrast, SLMV formation was enhanced 2.5-fold in Q67Lrab4 cells (▪) and inhibited in S22Nrab4 cells (●). Data represent the distribution of ¹²⁵I-Cl 604.1 in SLMVs as percentage of internalized antibody in the endosome donor, and are a representative of four independent experiments.