Lecture 22 Flashcards

1
Q

Explain the process of epinephrine binding to a beta-adrenergic receptor?

A
  1. epinephrine binds to the receptor
  2. The occupied receptor leads to displacement of GDP to GTP, thus activating Gs
  3. Gs subunit moves to adenylyl cyclase and activates it
  4. adenylyl cyclase catalyzes the formation of cAMP
  5. PKA (protein kinase A) is activated by cAMP
  6. PKA phosphorylates cellular proteins, which leads to a cellular responce
  7. cAMP is degraded, thus deactivation of PKA
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the generally happens when glucagon binds to the glucagon receptor?

A
  1. ligand binding
  2. Gs (alpha) activation
  3. adenylate cyclase activation
  4. increased production of cAMP
  5. activates PKA
  6. protein cascade
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What kind of receptor is the glucagon receptor?

A

Beta-adrenergic receptor

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

What are the step to adenylate cyclase activation?

A
  1. Ligand binds to the G-protein receptor
  2. The activated receptor interacts with the G-protein and the G alpha subunit is released by phosphorylation
  3. GTP bound G alpha subunit activates adenylate cyclase
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What does adenylate cyclase do exactly?

A

catalyzes the reaction of ATP to cAMP

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

What does cAMP do?

A

it binds to protein kinase A and activates it

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

Where is the phosphate group placed on the protein?

A

Either serine or theronine

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

How is the signal terminated?

A
  1. GTP gets converted back to GDP by GTPase
  2. Phosphodiesterase enzyme hydrolyzes cAMP to AMP
  3. ligand dissociates from receptor
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What molecules inhibit inhibit cyclic nucleotide

phosphodiesterase and prolong effects of cAMP?

A

Caffeine and theophylline

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

How does cAMP impact gene regulation?

A

cAMP phosphorylates CREB to CREB-P, which can then enter the nucleus and impact gene expression

either decrease or increase expression

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

what does the binding of a ligand to the alpha-2-adrenergic receptor do?

A

This activates the Gi (alpha)

this inhibits adenylate cyclase

reduces cAMP levels

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What does ADP-ribosylation do?

A

leads to the inactivation of target proteins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Explain what the cholera toxin does?

A

Leads to the continuous activation of the Gs alpha protein

Thus the cell has a constant level of cAMP in the cell

This leads to the CFTR channel always being open

result:
watery diarrhea

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Explain what the pertussis toxin does?

A

The Gi alpha protein is continuously inactive

Thus increased levels of cAMP in respiratory cells

result: whooping cough

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Explain the alpha-1-adrenergic receptor pathway?

A
  1. epinephrine or norepinephrine bind to the receptor
  2. This activates Gq alpha
  3. That G-protein activates phospholipase C
  4. That forms the second messengers (IP3, Ca, and DAG)
  5. Activates protein kinase C
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What does phospholipase C do?

A

This enzyme cleaves PIP2 into IP3 and DAG

17
Q

What does the IP3 protein do?

A

This protein leads to the release of Ca from the ER

18
Q

cGMP does what?

A

Second messenger in smooth muscle relaxation,

platelet aggregation and in visual system

19
Q

What is the important of nitric oxide (NO)

A

Activates Protein kinase G which phosphorylates various proteins

Vascular smooth muscle relaxation by leading to
phosphorylated myosin light chain kinase and inhibits it

vasodilation

20
Q

What is the pathway of NO?

A
  1. activates guanylate cyclase
  2. increase cGMP levels
  3. activates protein kinase G
  4. vasodilation