Enzyme limited step is usually valves:
PFK-1 catalyze the reaction to convert fructo-6-phosphate into fructo-1,6-bisphosphate, it is irreversible and is enzyme limited.
Hexokinase catalyzes the reaction to convert glucose into glucose-6-phosphate, it basically traps the glucose in the cell and it is enzyme limited
Pyruvate kinase catalyze the reaction to convert phosphoenolpyruvate to pyruvate, the reaction is exergonic and it is enzyme limited.
Therefore the only substrate limited choice above is aldolase.
Pyruvate kinase is allosteric activated by fructo-1,6-bisphosphate. I googled on this one.
It doesn't make sense for ATP or citrate to activate pyruvate because they are products. I am just unsure if it is fructo-1,6-bisphosphate or fructo-2,6-bisphosphate.
It is allosterically inhibited by ATP and alanine. It makes sense for ATP because it is the end product, alanine I just googled it.
When blood glucose is high, fructo-6-phosphate accumulates in the muscle due to downstream inhibition of PFK-1. This leads to an inhibition of the upstream enzyme hexokinase, and ultimately glucose remains in the blood and is taken up in liver cells. Liver glucokinase is not inhibited by its product, so liver cells continue to take up glucose.
Glucose is shunted towards fatty acid synthesis, and
Glucose is used to synthesize glycogen.
Both are used for energy storage, as excess energy must be stored.
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