1. Pro-opiomelanocortin-Related Peptides, Prohormone Convertases 1 and 2 and the Regulatory Peptide 7B2 are Present in Melanosomes of Human Melanocytes 
Eva M.J. Peters, Desmond J. Tobin, Karin U. Schallreuter 
Journal of Investigative Dermatology 
Volume 114, Issue 3, Pages (March 2000)
DOI: /j x
Copyright © 2000 The Society for Investigative Dermatology, Inc Terms and Conditions

2. Figure 1
Computer-generated evaluation sheet demonstrating the most characteristic distribution of PC2. From left to right the different cells represent different morphologies of melanocytes at different degrees of differentiation. At the far left the most differentiated type of melanocyte is depicted, on the far right, the most undifferentiated, fibroblast-like. Dots implicate immunoreactive granules displaying different staining intensities.
Journal of Investigative Dermatology  , DOI: ( /j x)
Copyright © 2000 The Society for Investigative Dermatology, Inc Terms and Conditions

3. Figure 2
ACTH 17–39, ACTH 1–10, α-MSH, PC1, 7B2, and PC2 expression in cultured epidermal human melanocytes. Methanol fixed cells cultured on chamber slides, were incubated with the primary antibodies against ACTH 17–39 (a,h), α-MSH (b), ACTH 1–10 (c), PC1 (d), 7B2 (e), PC2 (f), NKI beteb (g), or in PBS containing 0.2% BSA and 0.3% Triton X-100 (negative control, i). This incubation was followed by incubation with peroxidase conjugated secondary antibodies and AEC development yielding a reddish-brown color that highlights immunoreactive structures. (a–f) Mainly granular structures are highlighted. These structures are primarily located in the tips (small arrows) and close to the nucleus (arrowheads) of mature, melanin- producing melanocytes. At least one other population of melanocytes is present, which shows little or no immunoreactivity (large arrows) and low melanogenicity. (g) NKI beteb immunoreactivity highlights melanosomes in the tips (arrows) and around the nucleus (arrowheads) of mature, melanin-producing melanocytes. Note the similarity in their distribution with the distribution of immunoreactive granules in (a–f). (h) A subgroup of cells incubated with the primary antibody against ACTH 17–39. Note the large strongly immuno- reactive granules alongside the cell-membrane (arrowheads) close the nucleus (N) but not in the dendrites (arrows). (i) The negative control does not contain reddish-brown granular structures whereas melanin granules are readily detectable by their brown color.
Journal of Investigative Dermatology  , DOI: ( /j x)
Copyright © 2000 The Society for Investigative Dermatology, Inc Terms and Conditions

4. Figure 3
Immunoelectronmicroscopy of cultured epidermal human melanocytes. Immunoelectronmicroscopy was performed on hydrophilic resin embedded cultured melanocytes (passage 3) as indicated in the Materials and Methods section. Electronmicrographs show melanocytes without counter-staining, to allow full visibility of the 5 nm gold particles used to label immunoreactive sites. The different stages (I–IV) of melanogenesis can be determined by the increasing electron density of the characteristically shaped melanosomes. (ai) PC1 labeling gold particles are associated with stage II and III melanosomes (arrows). The frame is indicating the origin of the insert. (aii) Insert to (ai) showing gold particles in a stage II (top) and a stage III (bottom) melanosome (arrowheads) at high magnification. (bi) PC2 labeling gold particles are associated with stage II and III melanosomes (arrows). The frame is indicating the origin of the insert. (bii) Insert to (bi) showing gold particles in a stage II melanosome (arrowheads) at high magnification. (ci) 7B2 labeling gold particles are associated with the smooth ER and a putative stage I–II melanosome (arrow). The frame is indicating the origin of the insert. (cii) Insert to (ci) showing gold particles in the smooth ER (arrowheads) at high magnification.
Journal of Investigative Dermatology  , DOI: ( /j x)
Copyright © 2000 The Society for Investigative Dermatology, Inc Terms and Conditions

5. Figure 4
α-MSH and PC2 expression in the human epidermis. Seven micrometer cryosections were obtained from breast-skin samples from a female elective plastic surgery patient aged 47 and processed for immunohistochemistry as described in the Materials and Methods section. D, dermis. (a) α-MSH immunoreactivity is found in all layers of the epidermis (E), but is most pronounced in dendritic cells in the basal layer (arrows). (b) PC2 immunoreactivity resembles the α-MSH immunoreactivity pattern with strongly positive dendritic cells in the basal layer (arrows).
Journal of Investigative Dermatology  , DOI: ( /j x)
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6. Figure 5
Western blotting of cultured human melanocytes. Human skin derived melanocytes (passage 8), harvested in NP-40 were stained with the antibodies against PC1, 7B2, and PC2. PC1 and PC2 yielded positive bands in a kilodalton range similar to that found for activated and nonactivated isoforms of the enzyme in the pituitary. 7B2 did not yield positive bands possibly due to the applied extraction method.
Journal of Investigative Dermatology  , DOI: ( /j x)
Copyright © 2000 The Society for Investigative Dermatology, Inc Terms and Conditions