DEFINITION of 'Commercial'. Relating to commerce. In the investment field, the term commercial is generally used to refer to a trading entity engaged in business activities that are hedged by positions in the futures or options markets.
The melanocortin 1 receptor controls which type of melanin is produced by melanocytes. When the receptor is activated, it triggers a series of chemical reactions inside melanocytes that stimulate these cells to make eumelanin. If the receptor is not activated or is blocked, melanocytes make pheomelanin instead of eumelanin.
Melanocytes are the cells that synthesize pigment. Through a series of enzymatic reactions these cells efficiently produce melanin pigment that determines skin color. Once it is formed, melanin is packaged into tiny vesicles called melanosomes. The melanocyte has tiny tentacles that it uses to transfer melanosomes to other skin cells. It is interesting to note that dark-skinned patients do not have more melanocytes but instead have melanocytes with more pigment producing power.