We have a reversible process that is catalyzed by phosphlucose isomerase. We transform glucose six phosphate into its isomer fructosex phosphate and then this third step takes place in which we transform the fructosex phosphate into this committed molecule fructose one six bisphosphate by phosphorptokinase. So let's suppose we're at rest and what that means is we're going to have high energy charge value. We're going to have many ATP molecules what will that cause? Well, the ATP molecules will bind onto the regulatory sides of phosphorptokinase, inhibiting that molecule. And if this molecule is inhibited, the enzyme is inhibited, this fructosex phosphate cannot go on to the next molecule.