Metabolism control points

Question 1

What are the control points for glycolysis?

Answer 1

1. Transport of glucose into cell (muscle)
2. Hexokinase (muscle), glucokinase (liver)
3. Phosphofructokinase 1
4. Pyruvate kinase

Question 2

What are the regulators of glucose transport into cells?

Answer 2

Insulin (via GluT4 transporters)

Question 3

What are the regulators of phosphofructokinase 1?

Answer 3

Intracellular:

1. AMP +
2. F2,6BP + (liver, cardiac muscle)
3. F6P +
4. ATP -
5. Citrate -

Extracellular:

1. Adrenaline +/-
2. Insulin +/-
3. Glucagon -

Question 4

What are the regulators of F2,6BP synthesis?

Answer 4

• Insulin promotes dephosphorylation of PFK2/FBPase 2 complex. Activates liver PFK2.
• Glucagon promotes phosphorylation of PFK2/FBPase complex. Deactivates liver PFK2.
• Adrenaline promotes phosphorylation of PFK2/FBPase complex. Activates cardiac PFK2 and deactivates liver PFK2.

Question 5

What are the regulators of pyruvate kinase?

Answer 5

1. G6P +

Question 6

What are the control points for gluconeogenesis?

Answer 6

1. Glucose 6-phosphotase
2. FBPase 1
3. Pyruvate carboxylase

Question 7

What are the regulators of glucose 6-phosphotase?

Answer 7

1. Compartmentation into ER

Question 8

What are the regulators of FBPase 1?

Answer 8

1. AMP -
2. F2,6BP -
3. ATP

Question 9

What are the regulators of pyruvate carboxylase?

Answer 9

1. Acetyl-CoA +

Question 10

What are the control points for glycogen metabolism?

Answer 10

1. Glycogen synthase
2. Glycogen phosphorylase

Question 11

What are the regulators of glycogen synthase?

Answer 11

1. G6P +
2. Phosphorylation (via PKA/GSK) -
3. Dephosphorylation (via protein phosphotase 1) +

Question 12

What are the regulators of glycogen phosphorylase?

Answer 12

1. AMP +
2. Ca²⁺ +
3. G6P -
4. ATP -
5. Phosphorylation (via phosphorylase kinase) +
6. Dephosphorylation (via protein phosphotase 1) -

Question 13

What are the regulators of phosphorylase kinase?

Answer 13

1. PKA +

Question 14

What are the control points for the link reaction?

Answer 14

1. Pyruvate dehydrogenase

Question 15

What are the regulators of pyruvate dehydrogenase?

Answer 15

1. Phosphorylation (via PDH kinase) -
2. Dephosphorylation (via PDH phosphotase) +

Question 16

What are the regulators of PDH kinase?

Answer 16

1. Acetyl-CoA +
2. ATP +
3. NADH +
4. Pyruvate -

Question 17

What are the regulators of PDH phosphotase?

Answer 17

1. Ca²⁺ +
2. Insulin (liver, adipose) +

Question 18

What are the control points for the CAC?

Answer 18

1. Citrate synthase
2. Isocitrate dehydrogenase
3. α-ketoglutatate dehydrogenase

Question 19

What are the regulators of citrate synthase?

Answer 19

1. ATP -
2. Acetyl-CoA -
3. NADH -

Question 20

What are the regulators of isocitrate dehydrogenase?

Answer 20

1. ADP +
2. Ca²⁺ +
3. NADH -
4. ATP -

Question 21

What are the regulators of α-ketoglutarate dehydrogenase?

Answer 21

1. Ca²⁺ +
2. Succinyl-CoA -
3. NADH -

Question 22

What are the control points for β-oxidation?

Answer 22

1. Hormone-sensitive TAG lipase
2. Re-esterification of TAGs
3. Carnitine shuttle
4. NAD⁺ and FAD

Question 23

What are the regulators of hormone-sensitive TAG lipase?

Answer 23

1. Phosphorylation (via PKA) +
2. Dephosphorylation (via protein phosphotase) -

Question 24

What are the regulators of the carnitine shuttle?

Answer 24

1. Malonyl-CoA -

Question 25

What are the control points for fatty acid synthesis?

Answer 25

1. Acetyl-CoA carboxylase
2. Citrate shuttle
3. TAG synthase

Question 26

What are the regulators of ACC?

Answer 26

1. Citrate +
2. Dephosphorylation (via protein phosphotase) +
3. Acyl-CoA -
4. Phosphorylation (via AMPK) -

Question 27

What are the regulators of AMPK?

Answer 27

1. AMP +
2. ATP -

Question 28

What are the regulators of the carnitine shuttle?

Answer 28

1. Citrate +
2. NADH +
3. ATP +
4. Ca²⁺ -
5. ADP -

Question 29

What are the regulators of TAG synthase?

Answer 29

1. Glucose +
2. Insulin +