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. Author manuscript; available in PMC: 2008 Apr 24.
Published in final edited form as: Curr Biol. 2007 Nov 8;17(23):2030–2034. doi: 10.1016/j.cub.2007.10.051

Figure 5. xRab32 is Involved in Regulation of Melanosome Transport.

Figure 5

(A) xRab32 blocks melanosome aggregation by melatonin. The left panel is a bright-field image showing melanosome distribution before melatonin stimulation. The black arrows indicate EGFP-xRab32 transfected cells (inset) and the black arrowhead indicates a control cell. The right panel shows the distribution of melanosomes after 40 minutes of melatonin stimulation. EGFP-xRab32 overexpression in transfected cells (black arrows) completely blocks pigment aggregation by melatonin. Bars, 10 μm. This figure represents frames from Supplementary Movie 3.

(B) Recruitment of PKA by xRab32 to melanosomes is essential for inhibition. Xenopus melanophores were transiently transfected with EGFP-Rab9, EGFP-xRab32, or EGFP xRab32L186P. Transfected cells were treated with melatonin or MSH and scored into three groups (aggregated, partially dispersed, and dispersed). In each experiment, aggregated, partially dispersed, and dispersed cells are shown as white, gray, and black bars, respectively. n=100 for each condition. The experiment was repeated three times.

(C) xRab32 regulates melanosome movement upstream of PKA.

Xenopus melanophores were cotransfected with EGFP-xRab32 and constructs pNP210 or pNP211 encoding HA-epitope tagged active or inactive PKA inhibitor, PKI, respectively. Transfected cells were treated with melatonin or MSH, fixed, immunostained for HA and scored into three groups (aggregated, partially dispersed, and dispersed). In each experiment, aggregated, partially dispersed, and dispersed cells are shown as white, gray, and black bars, respectively. n=100 for each condition. The experiment was repeated three times.