Regulation of Metabolic Pathways Flashcards
Glycolysis major regulatory enzymes
Glucokinase, PFK1, pyruvate kinase, pyruvate dehydrogenase
Glucokinase
Glucose –> G6P
Insulin (+)
PFK1
F-6-P --> F-1,6-BP Glucagon (-) by decrease in F,2-6-BP F-2,6-BP (+) AMP (+) Citrate (-) ATP (-)
Pyruvate kinase
PEP --> Pyruvate F-1,6-BP (+) ATP (-) Alanine (-) Glucagon --> High PKA (-)
Pyruvate dehydrogenase
(+): Insulin, F-1,6-BP, ADP
(-): Glucagon, ATP, Alanine, Acetyl CoA, NADH
Citric acid cycle major regulatory enzyme
Isocitrate dehydrogenase (Isocitrate –> a-Ketoglutarate)
(+) ADP, Ca2+
(-) ATP
a-Ketoglutarate dehydrogenase (a-Ketoglutarate –> succinyl CoA)
(+) Ca2+
(-) NADH, succinyl-CoA
Gluconeogenesis regulatory enzymes
(1) Pyruvate carboxylase (Pyruvate –> OAA)
- (+) Acetyl CoA
(2) PEP carboxykinase (OAA –> PEP)
(3) Fructose-1,6-BPase
- (+) Citrate, Glucagon
- (-) AMP, F-2,6-BP
How glucagon works
Glucagon –> Adenylyl cyclase –> cAMP –> PKA –> phosphorylation of proteins involved with glycogenolysis, gluconeogenesis, FA breakdown
Protein phosphorylation
Activates enzymes that increase blood glucose and fatty acid breakdown. Inactivates enzymes that store glucose and fat. Glucagon promotes ppylation; insulin promotes deppylation
Glycogenesis regulatory enzyme
Glycogen synthase
(+) Insulin, glucose-6-phosphate
(-) Glucagon in liver, epinephrine in muscle
Glycogenolysis regulatory enzyme
Glycogen phosphorylase
(+) Ca2+ and epinephrine in muscle, glucagon in liver
Pentose phosphate pathway regulatory enzyme
Glucose-6-phosphate dehydrogenase
(-) NADPH
Fatty acid synthesis enzyme
Acetyl CoA carboxylase (Acetyl CoA –> malonyl CoA)
- (+) Insulin, citrate
- (-) Glucagon, palmitate
Lipolysis enzyme
Lipase
(+) Epinephrine
(-) Insulin
Beta-oxidation of fatty acids enzymes
Carnitine acyltransferase
(-) Malonyl CoA
