Melanocytes metabolic activity

The stratum basale (germinativum) is a metabolically active and rapidly dividing cell layer that serves as the source of the cells of the outer epidermis. Melanocytes are specialized neural cells located in the stratum basale. These cells produce the pigment melanin, which protects the animal against ultraviolet rarJia-tion and acts as a sunscreen. 

All this biochemical information points to a general role of the glutathione system in the metabolic activity of both eumelanic and phaeomelanic melanocytes. Hov/ever, whether glutathione is also specifically involved in the biosynthesis of the cysteinyldopas required for phaeomelanin formation remains to be determined, and the answer obtained will unquestionably contribute to our understanding of the synthetizing activity of mammalian melanocytes. 

FIGURE 142.5 Proposed mechanism of psoralen-fatty-acid adduct action on protein kinase C (PKC). UV-A irradiation induces a covalent adduct between psoralen and phospholipids that stimulates phospholipase A2. The enzyme hydrolizes the photocompound, producing psoralen-fatty-acid adduct, which in turn, activates protein kinase C. The activation of this phosphorylating enzyme can modulate cell function and metabolism, i.e., stimulating melanogenesis in melanocytes. 

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