Lecture 23

Question 1

What are the Gs protein receptor

Answer 1

b-adrenergic receptors, glucagon,

histamine, serotonin

Question 2

What are the signalling pathways of Gs

Answer 2

Stimulatory, increase cAMP

Question 3

What are the Gi receptors

Answer 3

a2-adrenergic receptors

Question 4

What are the signalling pathway ofr Gi

Answer 4

Inhibitory, decrease cAMP

Question 5

What are the Gq receptors

Answer 5

a1-adrenergic receptors, some

muscarinic receptors; histamine

Question 6

What are the signalling pathway for Gq

Answer 6

IP3, DAG

Increase cytoplasmic Ca++

Question 7

What are the Gt receptors

Answer 7

Light receptors in eye

Question 8

What are the signalling pathway for Gt

Answer 8

Transducin, Increase cGMP
phosphodiesterase (catalytic)
Decrease cGMP

Question 9

What happens when Glucagon & Adrenalin acts on the same Gs protein

Answer 9

Increase adenylate cyclase
à increase CAMP
Same enzymes activated
Act additively

Question 10

What happens about NO is synthesized in the endothelial cell

Answer 10

diffused to vascular myocyte and activates cytosolic guanylate cyclase which is then broken down into nitrate and oxide

Question 11

What are the water soluble hormones

Answer 11

• Amines (other than thyroid hormones)
• Peptides & proteins
• Eicosanoids

Question 12

What are the lipid soluble hormones which are able to cross the cell mmembrane

Answer 12

• Steroids
• Thyroid hormones (amines)
• Nitric oxide

Question 13

What are class 1 Nuclear Receptors

Answer 13

Ligand binding to type I
nuclear receptors (NR) in
the cytosol

Question 14

What are Class II Nuclear Receptors

Answer 14

1. NR located in nucleus
2. Thyroid hormone receptor (TR)
   heterodimerized to the retinoic
   acid receptor RXR.
3. TR is bound to corepressor
   protein. OFF