3 L1 GPCRs

Question 1

Compare GPCR v Ion channel activation

Answer 1

Both- Binding of agonist causes conformational change in receptor protein
Ion- Conformational change opens gate for ion flow
GPCR- More stuff happens

Question 2

Describe GPCR activation

Answer 2

Following conformational change, GTP replaces GDP on alpha subunit - GTP bound alpha subunit breaks off from receptor complex - GTP bound alpha subunit interacts with target protein to modify cell signalling

Question 3

G protein subunits and subtypes

Answer 3

Subunits- a, B, y
a subtypes- i, s, q

Question 4

Describe the roles of IP3 and DAG

Answer 4

IP3 increases free Ca from ER
DAG activates PKC (protein kinase C)

Question 5

Describe Gs proteins

Answer 5

D1 type receptors - Activates adenyl cyclase - Amplifies cAMP - Activates PKA - Activates Na channels

Question 6

Describe Gi proteins

Answer 6

D2 type receptors - Deactivates adenyl cyclase - Decreases cAMP - Activates AK channels (GIRK) - Closes Ca channels

Question 7

AMPA and GABA

Answer 7

AMPA- Na ion channel that causes neurons to fire
GABA- Cl ion channel that stops neurons from firing

Question 8

What does GIRK do

Answer 8

GIRK pushes K out of the postsynaptic neuron making MP more negative- neuron does not fire

Question 9

3 receptors that are coupled to Gq proteins

Answer 9

Serotonin - Muscarinic - Alpha1 (noradrenaline)

Question 10

Where are M3 (Muscarinic type 3) found

Answer 10

Intestinal smooth muscle cells

Question 11

Describe M3 (Muscarinic type 3) pathway

Answer 11

Ach activates M3 receptors to activate PLC - Produces IP3 - Releases Ca from SR - Ca binds to calmodulin - Calmodulin activates myosin light chain kinase - Phosphorylation of myosin light chains and muscle contraction