Some mono- and disaccharides act as signaling molecules that regulate gene expression. In budding yeast, the glucose sensor membrane Rgt2 Snf3 and activate signaling pathways regulating the expression of genes encoding glucose transporters . GPR1 membrane glucose receptor interacting with the G protein activates a signal transduction chain comprising the adenylate cyclase and protein kinase A. Results of many studies suggest that changes in intracellular levels of glucose by heksokinazę2 ( Hxk2 ) .