Pigmentation Revisited

By: Peter T. Pugliese, MD

Posted: February 26, 2009, from the March 2009 issue of Skin Inc. magazine.

Images

• Figure 1: Cross Section of Human Embryo
• Figure 2: Migration of Melanoblasts
• Figure 3: Tyrosinase in Stage II Melanosome
• Figure 4: Synthesis of Melanin
• Figure 5: Melanin
• Figure 6: Stimulators of Melanogenesis
• Figure 7: Melanosomes to Keratinocytes

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g Lysosomes are hollow blister-like structures that serve as cellular disposal systems by breaking down waste products, including discarded protein.

i MC1R gene converts pheomelanin to eumelanins.

h Lack of this enzyme causes a disease known as phenylketonuria (PKU) that is associated with mental disability. The incurable condition is inherited, but fully treatable with a diet low in the amino acid phenylalanine and high in tyrosine. It is easily detected in infants by a urine test. The children afflicted with PKU have blond hair and blue eyes.

j Transcription factors are peptides or proteins that enter the nucleus and activate genes.

k The Rho family of GTPases is a family of small (~21 kDa) signaling proteins and is a subfamily of the Ras superfamily. The Rho group regulates many aspects of intracellular action dynamics. Rho proteins have been described as molecular switches that play a role in cell proliferation, apoptosis, cell division, gene expression and many other common cellular functions.