Gluconeogenesis Flashcards
What enzyme(s) are involved in Bypass 1 of gluconeogenesis?
PEPCK and pyruvate carboxylase
What enzyme(s) are involved in Bypass 2 of gluconeogenesis?
Fructose-1,6-bisphosphate
What enzyme(s) are involved in Bypass 3 of gluconeogenesis?
Glucose-6-phosphatase
What are “bypasses” in gluconeogenesis?
The reverse reactions of the highly regulated reactions of glycolysis
How many ATPs, GTPs, and NADHs are spent in gluconeogenesis?
4 ATP, 2 GTP, 2 NADH
How many cellular components does gluconeogensis span?
3
What are the cellular components that gluconeogenesis spans?
Mitochondrial matrix, cytosol, ER
What is the role of pyruvate carboxylase?
It adds carbon to pyruvate.
What enzyme does Acetyl-CoA allosterically activate?
Pyruvate carboxylase
What is the cofactor of pyruvate carboxylase?
Biotin
What is the role of biotin?
It transfers CO2 from HCO3- onto pyruvate
What kind of reaction is the pyruvate carboxylase reaction?
Anaplerotic
What is pyruvate converted to in Bypass 1?
Oxaloacetate
What is oxaloacetate converted to?
Malate
How is malate transported to the cytoplasm?
The malate-aspartate shuttle
What is malate converted back to in the cytosol?
Oxaloacetate
What is oxaloacetate converted to in the cytosol?
PEP
What enzyme helps produce PEP?
PEPCK
How does PEPCK help produce PEP?
It phosphorylates and decarboxylates oxaloacetate
What does Fructose-1,6-Bisphosphatase produce?
Fructose-6-phosphate
Is the FBPase-1 reaction favorable?
Yes
What does glucose-6-phosphatase do?
It cleaves off the phosphate group, so it releases free glucose
Where is glucose-6-phosphatase used?
Glycogen metabolism and gluconeogenesis
Where is glucose-6-phosphatase localized?
ER membrane
Why is glucose-6-phosphatase localized in the ER membrane?
Because once glucose is created, it is prone to being broken down by the glycolytic enzymes in the cytosol
What is the structure of glucose-6-phosphatase?
9 transmembrane helices
What helps with transport of glucose?
Hexokinase IV and GLUT2
How is reciprocoal regulation of the irreverisble reactions in glycolysis and gluconeogenesis achieved?
Kinetic control
What enzyme regulates PFK-1 and FBPase-1?
Fructose-2,6-bisphosphate
What does Fructose-2,6-bisphosphate activate?
PFK-1
What does Fructose-2,6-bisphosphate inhibit?
Fructose-1,6-bisphosphatase
What does PFK-1 activate?
Fructose-1,6-bisphosphate
What does Fructose-1,6-bisphosphatase activate?
Fructose-6-phosphate
What are PFK-2 and FBPase-2 regulated by?
Fructose-6-phosphate
What enzyme is activated in the fed state?
PFK-2
What does PFK-2 promote?
Glycolysis
Is PFK-2/FBPase-2 phosphorylated or dephosphorylated in the fed state?
Dephosphorylated
Is PFK-2/FBPase-2 phosphorylated or dephosphorylated in the fasted state?
Phosphorylated
What enzyme is activated when PFK-2/FBPase-2 is phosphorylated?
FBPase-2, thus producing F-6-P, and going through gluconeogenesis
What enzyme is activated when PFK-2/FBPase-2 is dephosphorylated?
PFK-2, thus producing F-2,6-BP, and going through glycolysis
