Figure 6.

Velocity gradient centrifugation demonstrates that POMC is sulfated in trans-Golgi/TGN but is processed in vesicular fractions corresponding to ISGs. A 15-cm dish of AtT-20 cells were pulse-labeled with [³⁵S]sulfate for 5 min, and the cells were harvested either without chase (A) or after a 15-min chase at 37°C (B). A PNS was prepared and loaded on a 0.3–1.2 M sucrose gradient. Radiolabeled products were recovered from each gradient by acetone precipitation and analyzed by SDS-PAGE (on a 15% gel) and PhosphorImager.