Glucose repression may involve processes with different sugar kinase requirements

Adding glucose to Saccharomyces cerevisiae cells growing among nonfermentable carbon sources leads to glucose repression. This process may be resolved into several steps. An early repression response requires any one of the three glucose kinases present in S. cerevisiae (HXK1, HXK2, or GLK1). A late response is only achieved when Hxk2p is present.