Lecture 10- GPCRs signalling

Question 1

What does Gq(alpha) activation result in?

Answer 1

Activated PLC-beta to produce IP3 which releases calcium

Question 2

What are 2 kinds of second messengers generated by lipases?

Answer 2

1. Water soluble and able to diffuse through the cytoplasm e.g IP3
2. Hydrophobic molecules which remain in the membrane e.g DAG

Question 3

What can GPCRs activate and what in turn does this generate?

Answer 3

GPCRs activate PLC which can generate IP3 and DAG

Question 4

How can you monitor the localised activation of 2nd messenger enzymes in real time?

Answer 4

Imaging the location of fluorescent-tagged PKC

Question 5

How is PKC activated?

Answer 5

1. DAG binding causes dissociation of intramolecular pseudosubstrate domain from active site
2. Once activated, PKCs can provide either negative or positive feedback
3. Phosphorylation of PLC-beta provides negative feedback for GPCR signalling
4. This makes signalling transient and contribute to desensitisation

Question 6

What occurs after GaPCRs are activated and DAG is synthesised?

Answer 6

1. Recruits Munc13 to the membrane

2. Stimulates secretory vesicle docking to the PM preparing it for fusion

Question 7

What does calcium signalling regulate?

Answer 7

1. Synaptic transmission
2. Hormone secretion/synthesis
3. Fertilisation
4. Muscle contraction
5. Cytokinesis

Question 8

How is calcium influx into the cytosol regulated?

Answer 8

Regulated by channels in the PM and ligand gated channels on the ER

Question 9

What are B-stores operated channels made up of ORAI and gated by STIM responsible for?

Answer 9

Responsible for calcium store refilling and maintaining ER calcium levels