Phosphorylation of glucose
One ATP is spent to add a phosphate to glucose. The charged phosphate traps glucose inside the cell.
Glycolysis · irreversibleAdenosine diphosphate, formed when ATP gives up a phosphate and recharged to ATP in the payoff phase.
ADP is what remains when ATP has transferred a phosphate group. Cells can add a phosphate back to recharge it as ATP.
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One ATP is spent to add a phosphate to glucose. The charged phosphate traps glucose inside the cell.
Glycolysis · irreversibleA second ATP adds a phosphate to carbon 1. This commits the sugar to glycolysis and is the pathway's main control point.
Glycolysis · irreversible1,3-Bisphosphoglycerate gives a phosphate to ADP and makes ATP. Across both three-carbon halves, this repays the two ATP invested.
Glycolysis · reversiblePEP gives its phosphate to ADP, forming ATP and pyruvate. This second ATP-making step is where glycolysis turns a net profit.
Glycolysis · irreversiblePyruvate gains a carbon dioxide equivalent to form oxaloacetate, using ATP and biotin.
Gluconeogenesis · irreversibleATP synthase uses proton flow to drive ATP formation from ADP and phosphate.
Oxidative phosphorylation · irreversibleATP-citrate lyase provides cytosolic acetyl-CoA from exported citrate.
Fatty acid synthesis · irreversibleAcetyl-CoA carboxylase uses ATP and biotin to make malonyl-CoA.
Fatty acid synthesis · irreversibleMevalonate kinase phosphorylates mevalonate.
Cholesterol biosynthesis · irreversiblePhosphomevalonate kinase makes mevalonate 5-diphosphate.
Cholesterol biosynthesis · irreversibleMevalonate diphosphate decarboxylase produces the five-carbon isoprene unit IPP.
Cholesterol biosynthesis · irreversibleCPS1 uses two ATP to combine ammonia and bicarbonate into carbamoyl phosphate.
Urea cycle · irreversibleFGAM synthetase supplies another ring nitrogen from glutamine.
Purine nucleotide synthesis · irreversibleAIR synthetase closes the first purine ring.
Purine nucleotide synthesis · irreversibleSAICAR synthetase adds aspartate to CAIR using ATP.
Purine nucleotide synthesis · irreversibleThe CAD enzyme complex forms cytosolic carbamoyl phosphate from glutamine and bicarbonate.
Pyrimidine nucleotide synthesis · irreversible