Figure 5: ELKS targets RAB6 vesicles to melanosomes.

(a) Live imaging frame (basolateral imaging plane Z-1) of control- or ELKS-depleted MNT-1 cells expressing GFP-RAB6 and mCh-VAMP7. Localization of GFP-RAB6 to melanosomes (arrows), but not to Golgi area (arrowheads), was specifically lost upon ELKS depletion (× 2.5 area). (b) Number of RAB6 vesicles quantified per cell (n) on live imaging frames in control- and ELKS-depleted MNT-1 cells presented as mean±s.e.m. (n=14–16, 3 independent experiments). (c) Quantification of the number of cells (n) harbouring GFP-RAB6 to melanosomes (siControl, n=105; siELKS, n=128). Data are normalized to control and presented as mean±s.e.m. (three independent experiments). (d) Pearson’s correlation coefficient of green (GFP-RAB6) and red (mCh-VAMP7) signal intensities in Control- (67 cells) or ELKS- (24 cells) depleted cells (four independent experiments). (e–g) Characterization of the dynamics of GFP-RAB6-positive vesicles in control- or ELKS-depleted MNT-1 cells. Comparison of velocity (e), track time (f) and fraction of track time in pause (g) presented as scattered plots (Mean±s.e.m.; see Supplementary Table 1). Scale bars, 10 μm (a); two tailed, Unpaired t test (b–g); ***P<0.001; ****P<0.0001; n.s., non significant.