Phosphofructokinase, a key regulatory enzyme in glycolysis, catalyzes the phosphorylation of fructose-6-phosphate to fructose-1,6-biphosphate. The members belong to a subfamily of the PFKA family (cd00363) and include bacterial ATP-dependent phosphofructokinases. These are allosrterically regulated homotetramers; the subunits are of about 320 amino acids.