Session 2: Intracellular Signalling Pathways Flashcards Preview

Sem 1: Pharamacology and Physiology > Session 2: Intracellular Signalling Pathways > Flashcards

Flashcards in Session 2: Intracellular Signalling Pathways Deck (18):
1

Define an agonist ligand.

Binds to a receptor and activates it

2

Define and antagonist ligand.

Binds to a receptor but does not activate it (blocks the effects of agonists at the receptor)

3

Name 4 common features of GPCRs.

1. Single polypeptide chain
2. 7 transmembrane spanning regions (7TM)
3. Extracellular N terminal
4. Intracellular C terminal

4

What results from a ligand binding to a GPCR

Conformational change

5

How many subunits are G proteins made of?

3 (alpha unit and a beta-gamma unit)

6

How does the GPCR-G protein interaction activate the G protein?

Causes GTP to exchange for GDP on the alpha subunit which then dissociate. These are now free to interact with secondary messenger proteins.

7

Once dissociated, how do the alpha and beta-gamma subunits of a G protein reform an inactive heterotrimetric complex?

The GTPase hydrolysises the GTP back to GDP

8

If adrenaline binds to a beta adrenoceptor which G protein alpha subunit is coded for and what is its consequence?

Gs (stimulatory) increase in adenylyl cyclase

9

What is the affect of cholera toxin (CTx)?

Gs cannot be switched off

10

What is the effect of pertussis toxin (PTx)?

Gi- can't be switched on

11

What is adenylyl cyclase used to convert?

Convert ATP into cyclic AMP

12

How does cyclic AMP continue the cascade?

Catalytic subunits phosphorylase target proteins (PKA- protein kinase reactions)

13

What is phospholipase C used to convert?

PIP2 to IP3 and DAG

14

Name 2 calcium ATPases

1. PMCA
2. SERCA

15

Name once calcium transporter mechanism.

Na+/Ca2+ exchanger (NCX)

16

TRUE OR FALSE: the plasma membrane is permeable to calcium

False- calcium is toxic in our cells and therefore is kept around an intracellular concentration of 1x10^-7

17

What's another name for calcium induced calcium release?

Ryanodine receptors

18

Why are cell signalling pathways important?

Signal amplification