TYRP1 does not accumulate in STX13-containing early endosomes in melanocytes that either lack AP-3 or express an AP-3δ variant that cannot bind VAMP7. (A–D) Melan-mh cells that were untransduced (A) or transduced to express WT AP-3δ (melan-mh: AP-3δ^WT; B) or the VAMP7 nonbinding variants AP-3δ^mut1 (C) or AP-3δ^mut2 (D) were fixed, immunolabeled for TYRP1 and STX13, and analyzed by dIFM. Shown are separate images of TYRP1 (left) and STX13 (middle) labeling; a merged image is shown at right. Boxed regions are magnified sevenfold in the insets. Arrowheads point to TYRP1-labeled structures that lack labeling for STX13. Scale bar, 10 µm; inset scale bar, 1 µm. These images are from the same cells as those shown in Fig. 1, A–D. (E) Quantification (mean ± SEM) of the percentage of structures labeled for TYRP1 that also label for STX13.