Regulation of phosphofructokinase (PFK).

<p>PFK converts fructose-6-phosphate (F6P) to fructose-1,6-diphosphate (F16DP), can be inhibited by ATP, citrate and fatty acids (FA) and activated by ADP, AMP and fructose-2,6-diphosphate (F26DP). F26DP concentrations depend on 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 3 (PFKFB3) activity converting F6P to F26DP and vice versa. In addition, intracellular FA concentrations depend on fatty acid binding proteins (FABP) which mediate their uptake and intracellular transport. Red and green colours indicate decreased/increased abundance of metabolites/mRNA in producer cultures.