Question

what is the clear mechanism of the action of glucagon in glycolysis and gluconeogenesis? such as phosphorylation/dephosphorylation, transcriptional control....

they can be explained?

thanks

Answer 1

Glucagon increases the concentration of glucose in the blood by promoting gluconeogenesis and glycogenolysis. Glucagon turns off glycolysis in the liver, causing glycolytic intermediates to be shuttled to gluconeogenesis.

Mechanism

Glucagon binds to the glucagon receptor, a G protein-coupled receptor, in the plasma membrane. This activates G protein,it undergoes a conformational change that results in the replacement of the GDP molecule at the alpha subunit with a GTP molecule. The alpha subunit specifically activates adenylate cyclase.

Adenylate cyclase givesncAMP which activates protein kinase,which activates phosphorylase kinase, which then phosphorylates glycogen phosphorylase b converting it into the active form called phosphorylase a
. Phosphorylase a is the enzyme responsible for the release of glucose 1-phosphate from glycogen polymers

The coordinated control of glycolysis and gluconeogenesis in the liver is adjusted by the phosphorylation.