GAL2 is a gene found in the yeast species Saccharomyces cerevisiae. It encodes a protein that plays a crucial role in the metabolism of galactose, a type of sugar. When galactose is present, GAL2 helps transport it into the cell, allowing the yeast to utilize it as an energy source. The expression of GAL2 is regulated by the GAL regulatory system, which responds to the availability of galactose. This system ensures that the yeast only activates the genes necessary for galactose metabolism when the sugar is present, optimizing energy use and maintaining cellular efficiency.