What is the variable that affects enzyme function in the example of phosphofructokinase-1?

This question is incomplete

Explanation:

The question is incomplete because the example referred to was not stated. However, phosphofructokinase-1 is a key enzyme in glycolysis; it converts/phosphorylates fructose-6-phosphate to fructose-1,6-bisphosphate in the presence of ATP to release ADP. It is a regulatory enzyme in this pathway (glycolysis) because it's function can be affected by an increased ATP to ADP ratio which inhibits the enzyme (phosphofructokinase-1) and indeed glycosis itself.

it depends on how much it could carry.