Fig. 8. Scheme for Pmel17 trafficking. Pmel17 is sorted from the Golgi to stage I melanosomes directly or indirectly according to whether µ1B is expressed. In melanocytic cells expressing µ1B (left side, black arrows), Pmel17 (85 kDa) is sorted from the TGN either to recycled endosomes or directly to a localized region in the plasma membrane via CCV containing µ1B. Pmel17 is then endocytosed and sorted to stage I melanosomes via AP2. In melanocytic cells that do not express µ1B (right side, gray arrows), default sorting of Pmel17 to the entire surface of the plasma membrane may be mediated by glycosylation or by other unknown determinants. Again, endocytosis and sorting to stage I melanosomes is via AP2. In both cases, the mPmel17 (100 kDa) resulting from its rapid processing and minimal presence in the plasma membrane, is sorted directly to melanosomes, probably via AP1A (white central arrow).