What are two pathways in which PEPCK is an important enzyme?

What are two pathways in which PEPCK is an important enzyme?

The biosynthetic pathways of gluconeogenesis (a), glyceroneogenesis (b), and serine synthesis (c) are outlined, as is the recycling/oxidation of the carbon skeletons of amino acids back into the citric acid cycle (d) as acetyl-CoA for subsequent oxidation or conversion to fatty acids.

What is the role of mitochondrial PEPCK?

Despite catalyzing the same reaction, to date the only significant role reported in mammals for the mitochondrial isoform is as a glucose sensor necessary for insulin secretion. Silencing PEPCK-M lowers plasma glucose, insulin, and triglycerides, reduces white adipose, and depletes hepatic glycogen, but raises lactate.

Does PEPCK increase gluconeogenesis?

Thus, acute physiological hyperinsulinemia does not suppress PEPCK protein expression to a large enough extent to alter GNG flux to G6P in vivo. Elevated HGP in the diabetic state is associated with increased gluconeogenesis and also typically increased levels of PEPCK mRNA expression in animal models.

How is PEPCK regulation?

Acute regulation of PEPCK is achieved by modulating transcription of the gene, which is tightly regulated by cAMP (the mediator of glucagon and catecholamines), glucocorticoids and insulin.

What enzyme converts oxaloacetate to phosphoenolpyruvate?

PEPCK
PEPCK is another key rate-limiting gluconeogenic enzyme, catalyzing the conversion of oxaloacetate to phosphoenolpyruvate and water.

Does PEPCK use ATP?

PEPCK uses GTP or ITP, but not ATP, as a phosphate donor to form P-enolpyruvate. Most bacteria and yeast studied to date contain an ATP-linked enzyme, which has little sequence sim- ilarity to mammalian PEPCK.

Is PEPCK in the mitochondria?

Phosphoenolpyruvate carboxykinase (PEPCK) is an enzyme in the lyase family used in the metabolic pathway of gluconeogenesis. It converts oxaloacetate into phosphoenolpyruvate and carbon dioxide. It is found in two forms, cytosolic and mitochondrial.

What is gluconeogenesis pathway?

Gluconeogenesis (GNG) is a metabolic pathway that results in the generation of glucose from certain non-carbohydrate carbon substrates. Under conditions of prolonged fasting, acetone derived from ketone bodies can also serve as a substrate, providing a pathway from fatty acids to glucose.

What is the committed step in gluconeogenesis?

The “committed step”: fructose 6-phosphate → fructose 1,6- bisphosphate. Two triose compounds are isomerized and oxidized to retrieve ATP & NADH via glyceraldehydes 3-phosphate dehydrogenase. The pathway concludes with a strong, irreversible, ATP-producing step to make pyruvate.