Regulation. With the glucose phosphotransferase system, the phosphorylation status of EIIA can have regulatory functions. For example, at low glucose concentrations phosphorylated EIIA accumulates and this activates membrane-bound adenylate cyclase. Intracellular cyclic AMP levels rise and this then activates CAP (catabolite activator protein), which is involved in the catabolite repression system, also known as glucose effect. When the glucose concentration is high, EIIA is mostly dephosphorylated and this allows it to inhibit adenylate cyclase, glycerol kinase, lactose permease, and maltose permease. Thus, as well as the PEP group translocation system being an efficient way to import substrates into the bacterium, it also links this transport to regulation of other relevant proteins.