1. Lecture 22
Signaling at the cell surface continued (chapter 15)
G-proteins and G-protein coupled receptors
Visual cascade and Receptor adaptation

2. G-protein coupled Receptors: Rhodopsin (visual pigment)
out
Retinal (ligand) in
Natural ligand (retinal) is inside the cavity

3. Why vision is a kind of smell?

4. 7-TM domain G-protein coupled receptors (short list)
a, b adrenergic R
Muscarinic AChR
Dopamine R
Histamine R
Prostaglandin PGE1 R
GABAB R
Substance P R
Opiate R
ADH (vasopressin VR1) R
Angiotensin R
Bradykinin R
Glucagon R
Ca2+ R
Olfactory receptors (?)
Taste receptors
Rhodopsin
these ligands come from outside

5. Beta2 Adrenergic receptor

8. FRET experiments indicate that activation of G-proteins occurs within seconds

11. KACh channel is regulated by G beta-gamma
Gbg

13. The intracellular (second) messengers
Cyclases
Phospholipase
Ca2+