BIOL124 - Lecture 3 - Signal Transduction

HideShow resource information
  • Created by: Katherine
  • Created on: 10-03-16 11:50
What are the 2 stages of cell signalling?
Reception, transduction and response.
1 of 31
What is transduction?
Cascades of molecular interactions relaying signals form receptors to target molecules in cells.
2 of 31
Does signal transduction involve multiple steps?
Yes - it is a multistep pathway.
3 of 31
What are the molecules that relay a signal from receptor to response?
Proteins (mostly)
4 of 31
What do protein kinases?
Transfer phosphates from ATP to protein, in a process called phosphorlyation
5 of 31
Where does phosphorylation most commonly occur?
On serine, threonin (or tyrosine) residues
6 of 31
What does phosphorylation normally lead to?
Protein activation
7 of 31
What do protein phosphates do?
Remove phosphates from proteins.
8 of 31
What is the process which protein phosphates remove phosphates from proteins called?
Dephosphorylation
9 of 31
Phosphorlyation and dephosphorylation therefore act as a...
molecular switch - turning activities on and off or up or down.
10 of 31
The extracellular signal molecule that binds to the receptor is a pathways...
First messenger
11 of 31
What is a second messenger?
It is a small, non protein, water soluble molecule or ion that readily spreads throughout a cell by diffusion.
12 of 31
Second messengers participate in pathways initiated by...
GPCRs and RTKs
13 of 31
What are two common second messengers?
Cyclic AMP and calcium ions.
14 of 31
What is cAMP?
Cyclic AMP is a widely used second messenger
15 of 31
What does Adenylyl cyclase do?
It is an enzyme in the plasma membrane that converts ATP to cAMP in response to an extracellular signal.
16 of 31
cAMP can be broken down by what to form AMP, which is inactive?
Phosphodiesterase
17 of 31
What is Cholera initiated by?
Drinking water containing the bacterium vibrio cholerae.
18 of 31
What do the bacteria do?
They colonise the small intestine (forming a biofilm) and produce an enzyme that acts as a toxin.
19 of 31
How does Cholera effect G-proteins?
It affects a G-protein involved in regulating salt and water excretion.
20 of 31
How does Cholera affect G proteins, more detail?
The modified G protein is unable to hydrolyse GTP to GDP and is switched on. = COnstant activation of adenylate cyclase and contiunous production of cAMP. High cAMP levels activate the CFTR = efflux of Cl- ions
21 of 31
Why is calcium an important second messenger?
Because cells can regular its concentration.
22 of 31
Under normal conditions is intracellular calcium low or high?
It is very low
23 of 31
In order to keep cytoplasmic concentrations of calcium low, what happens?
Cytoplasmic protein is actively pumped into the ER and/or mitochondria.
24 of 31
Pathways leading to the release of calcium invovle:
Inositol triphosphate (IP3) and diacylglycerol (DAG)
25 of 31
What is CaM?
Calmodulin - a very specific calcium modulated protein that contain 4 Ca2+ binding sites
26 of 31
What does calcium binding do for CaM?
Calcium binding induces conformational changes allowing CaM to bind to other proteins causing activation or inactivation.
27 of 31
What are the 4 aspects of fine tuning that need to be considered?
Amplifying the signal, specificity of the response, overall efficiency of response, enhanced by scafforlding proteins, termination of signal.
28 of 31
What are scaffolding proteins?
They are large relay proteins to which other relay proteins are attached
29 of 31
How can scaffolding proteins increase signal transduction efficiency?
By grouping together different proteins involved in the same pathway.
30 of 31
Are inactivation mechanisms an important part of cell signalling?
Yes
31 of 31

Other cards in this set

Card 2

Front

What is transduction?

Back

Cascades of molecular interactions relaying signals form receptors to target molecules in cells.

Card 3

Front

Does signal transduction involve multiple steps?

Back

Preview of the front of card 3

Card 4

Front

What are the molecules that relay a signal from receptor to response?

Back

Preview of the front of card 4

Card 5

Front

What do protein kinases?

Back

Preview of the front of card 5
View more cards

Comments

No comments have yet been made

Similar Biology resources:

See all Biology resources »See all Signal Transduction resources »