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. Author manuscript; available in PMC: 2010 Jan 27.
Published in final edited form as: Nature. 2008 Jul 23;454(7208):1142–1146. doi: 10.1038/nature07163

Figure 3. Tyrosinase is present but inactive in BLOC-1-deficient melanocytes.

Figure 3

(a–j) Bright field microscopy analysis of BLOC-1− (melan-mu, a, b; melan-rp, e, f), BLOC-1R (melan-mu:MuHA, c, d), AP-3-deficient (melan-pe, i, j) and tyrosinase mutant (melan-c, g, h) mouse melanocytes treated with L- or D-DOPA for 3 h. Tyrosinase activity is indicated by melanin deposition in the presence of L-DOPA but not D-DOPA. Insets, boxed regions magnified 5X. Bars, 10 µm. Note melanin deposits were not observed in melan-mu (a) or control melan-c cells (g), and modest deposits were observed in melan-rp cells in which BLOC-1 is partially assembled (e). (k) Whole cell lysates of mouse melanocytes were fractionated by SDS-PAGE and immunoblotted with anti-tyrosinase antibody. Blots were reprobed with anti-tubulin antibody as a loading control. Right, molecular weight markers (kDa). Arrows, relevant bands. Note that tyrosinase protein levels are only mildly reduced in BLOC-1− melan-mu cells relative to BLOC-1R melan-mu: MuHA cells.