Galactose transport in Saccharomyces cerevisiae. I. Nonmetabolized sugars as substrates and inducers of the galactose transport system

The inducible galactose transport system in bakers' yeast carries out the facilitated diffusion of the nonmetabolized galactose analogues d-fucose and l-arabinose. This capacity depends on the activity of the Ga 2 gene. In some strains, d-fucose and l-arabinose are also gratuitous inducers. Mutants in which the inducibility of the galactose pathway enzymes is altered show a parallel alteration of the inducibility of the galactose transport system.