Protein control: (leyland) Carb metabolism 2 Flashcards

1
Q

Describe regulation of PFK-1 via F26BP

A

F26BP acts as an allosteric regulator

-> stabilises R state and activates PFK-1

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is PFK-2 and what does it do?

A

Phosphofructokinase-2 also known as fructose bisphosphatase-2 -> bifunctional enzyme

  • Controls intracellular conc. of F26BP in the liver
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

How is PFK-2 hormonally regulated in the liver?

A

2 domains (kinase/phosphatase) are not active at the same time -> hormonally regulated via phosphorylation/dephosphorylation

Glucagon stimulates PKA production -> PKA phosphorylates PFK-2 and activates phosphatase domain (+++ gluconeogenesis, — F26BP)

Insulin stimulates phospho-protein phosphatase -> removes phosphate group and activates kinase domain](+++ glycolysis, +++ F26BP)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Mechanisms of phosphofructokinase regulation?

A

Allosteric regulation by multiple modulators (PFK-1)

Hormonally mediated phosphorylation/dephosphorylation via insulin and glucagon (PFK-2)

Transcriptional regulation - up-regulated by insulin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Function of pyruvate kinase? products produced?

A

Substrate-level phosphorylation

Catalyses phosphate group transfer of phosphate group of phosphoenolpyruvate and adds it to ADP to create ATP

Results in molecule of pyruvate and molecule of ATP

Very negative delta G -> irreversible under physiological conditions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Hormonal mechanism of regulation of pyruvate kinase?

A

PKA mediated phosphorylation stimulated by glucagon inactivates pyruvate kinase

PP mediated dephosphorylation stimulated by insulin activates pyruvate kinase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Mechanisms of regulation of pyruvate kinase?

A

Allosteric regulation by multiple modulators

Hormonally mediated phosphorylation by glucagon

Transcriptional regulation - up-regulated by insulin (L-form only)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the function and mechanism of lactate dehydrogenase?

A

Reduces pyruvate to form L-lactate

-> Oxidises NADH to reform NAD+ allows continued glycolysis and ATP production

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Where/how is lactate recycled back to pyruvate?

A

The liver via the Cori cycle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Main sources forming glucose at the beginning of gluconeogenesis?

A

Lactate
Triacylglycerols
amino acids

How well did you know this?
1
Not at all
2
3
4
5
Perfectly