How do hormonal signals influence the activity of pyruvate kinase (PKL)?

Hormonal signals such as glucagon and insulin regulate pyruvate kinase (PKL) activity at both transcriptional and posttranscriptional levels. Glucagon promotes phosphorylation of PKL by protein kinase A (PKA), inhibiting its activity during low glucose availability. Conversely, insulin activates protein phosphatases that dephosphorylate PKL, reactivating it and promoting glycolysis when glucose levels are sufficient.