Biochemistry and Histology of Different Skin Types

<p>(A) Activation of the melanocortin 1 receptor (MC1R) promotes the synthesis of eumelanin at the expense of pheomelanin, although oxidation of tyrosine by tyrosinase (TYR) is required for synthesis of both pigment types. The membrane-associated transport protein (MATP) and the pink-eyed dilution protein (P) are melanosomal membrane components that contribute to the extent of pigment synthesis within melanosomes. (B) There is a gradient of melanosome size and number in dark, intermediate, and light skin; in addition, melanosomes of dark skin are more widely dispersed. This diagram is based on one published by <a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.0000027#pbio-0000027-Sturm1" target="_blank">Sturm et al. (1998)</a> and summarizes data from <a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.0000027#pbio-0000027-Szabo1" target="_blank">Szabo et al. (1969)</a>, <a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.0000027#pbio-0000027-Toda1" target="_blank">Toda et al. (1972)</a>, and <a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.0000027#pbio-0000027-Konrad1" target="_blank">Konrad and Wolff (1973)</a> based on individuals whose recent ancestors were from Africa, Asia, or Europe.