Summary of Pathways Rate Determining Enzymes Process Enzyme Glycolysis Phosphofructokinase-1 (PFK-1) Gluconeogenesis Fructose-1,6-bisphosphatase TCA cycle Isocitrate dehydrogenase Glycogen synthesis Glycogen synthase Glycogenolysis Glycogen phosphorylase HMP shunt Carbamoyl phosphate synthetase II De novo pyrimidine synthesis Glutamine-PRPP amidotransferase Urea cycle Carbamoyl phosphate synthetase I Fatty acid synthesis Acetyl-CoA carboxylase (ACC) Fatty acid oxidation Carnitine acyltransferase I Ketogenesis HMG-CoA synthetase Cholesterol synthesis HMG-CoA reductase