Title: The effect of fructose 2,6‐bisphosphate and AMP on the activity of phosphorylated and unphosphorylated fructose‐1,6‐bisphosphatase from rat liver
Abstract: Rat liver fructose‐1,6‐bisphosphatase was partially phosphorylated in vitro and separated into unphosphorylated and fully phosphorylated enzyme. The effects of fructose 2,6‐bisphosphate and AMP on these two enzyme forms were examined. Unphosphorylated fructose‐1,6‐bisphosphatase was more easily inhibited by both effectors. Fructose 2,6‐bisphosphate affected both K 0.5 and V max , while the main effect of AMP was to lower V max . Fructose 2,6‐bisphosphate and AMP together acted synergistically to decrease the activity of fructose‐1,6‐bisphosphatase, and since unphosphorylated and phosphorylated enzyme forms are affected differently, this might be a way to amplify the effect of phosphorylation.