Signal Transduction 3: Glucagon And Epinephrine Signalling

Question 1

Examples of low blood sugar (hypoglycaemia)?

Answer 1

Coma, brain damage

Question 2

Examples of high blood glucose levels (hyperglycaemia)?

Answer 2

Diabetes

Question 3

How many amino acids does glucagon have?

Answer 3

29

Question 4

First step of glucagon?

Answer 4

It binds to the receptor and activates it via a conformational change

Question 5

Second step in glucagon pathway?

Answer 5

The receptor activates the stimulatory G protein

Question 6

What are the overall steps of regulating glucose levels?

Answer 6

Similar to typical pathway- glucagon binds to 7TM receptor, activates G protein, then cyclic AMP, then protein kinase A, the phosphorylase kinase, then phosphorylase A (aka the phosphorylation cascade)

Question 7

What does glucogen breakdown do to blood glucose?

Answer 7

Increases it

Question 8

How is glycogen breakdown rapidly turned off?

Answer 8

1. Hormones that stimulate glucogen breakdown are no longer present
2. The inherent GTPase activity of G-alpha subunit inactivates G protein signalling
3. Phosphodiesterase converts cAMP into AMP, which does not stimulate protein kinase A
4. A protein Phosphatase removes phosphates from phosphorylase kinase and glycogen phosphorylase, thereby inactivating the enzymes

Question 9

What can also regulate the glycogen metabolism?

Answer 9

Hormone-triggered cAMP cascades which leads to the activation of protein kinase A and activates glycogen degradation- while at the same time, protein kinase A, along with glycogen synthase kinase, inactivates glucogen not synthase, shitting turn glycogen synthesis

Question 10

Why are glycogen breakdown and synthesis reciprocally regulated?

Answer 10

As fuel can be stored at the same time it’s used

Question 11

What does glucagon and epinephrine target?

Answer 11

Glucagon= liver
Epinephrine = muscle cell