Signal Transduction

Question 1

what is the homeostatic reflex arc?

Answer 1

Note the autonomic response

Question 2

Ligands: agonist vs antagonist

Answer 2

1. signal increase
2. signal decrease

Question 3

What are the classes for Biogenic Amine NTs?

Answer 3

1. catecholamines (NorE, Epi, Dopamine)
2. Esters (Ach)
3. Indolamines (Histamine, 5-HT)

Question 4

Catecholamines are sympathetic or parasympathetic?

Answer 4

Post-ganglionic sympathetic

Question 5

Acetylcholine is used where?

Answer 5

1. autonomic ganglia
2. skeletal muscle

(postganglionic parasympathetic)

Question 6

What are the peptide NTs?

Answer 6

dont need to memorize NVM

Question 7

Amino Acid NTs

Answer 7

1. Excitatory (glutamate, Aspartate)
2. inhibitory (GABA, Glycine)

Question 8

NT: other

Answer 8

Question 9

what are the steps of G-protein Cycling?

Answer 9

1. agonist binds receptor in lock and key
2. receptor associates with G-protein
3. GTP enters and replaces GDP
4. Aplha-GDP and Beta/gamma subunits dissociate and start activating downstream protiens
5. alpha subununit hydrolyes GTP
6. subunits reunite

the alpha subunit GTPase activity- this acts like a timer. Therefore, the subunit is on a timer, and the signal does not stay on forever.

Question 10

Different alpha subunits …?

Answer 10

have different downstreatm effects (2nd messengers/ion channels)

Question 11

B-gamma subunit

Answer 11

???
slide 13 (relisten)

Question 12

What are the three alpha subunit families?

Answer 12

s- stimulates AC
i- inhibits AC
q- phospholipidase C (ca2+ levels increase in the cell??)

Question 13

What does Adenylate Cyclase and cAMP do?

Answer 13

AC converts ATP-Mg2+ to cAMP

cAMP activates PKA

phosphodiesterases (PDE) get rid of CAMP (regulation). Everything is a balancing act.

Question 14

How does PKA activity affect function?

Answer 14

varies- can increase or decrease (enzymes, pumps, channels)

Question 15

what are the families of Adenylate cyclase?

Answer 15

ADCY1, ADCY2, …, ADCY10, just note that there are many families

isoforms differ in acticity modulation??

Question 16

what are the components of the PLC system?

Answer 16

the end result: increased intracellular Ca2+

Question 17

What are the components of the Guanylate Cyclase system?

Answer 17

• ca2+ calmodulin complex activates NO synthase (CM-Ca2+)

note the presence of PDE to break down cGMP (Viagra is an example, it prevents breakdown of cGMP resulting in vasodilation)

Question 18

NO is made where and acts where?

Answer 18

1. Vascular endothelial cells
2. nearby smooth muscle cells

it increases cGMP resulting in vasodilation

Question 19

ACh is found where?

Answer 19

PNS and CNS

Question 20

What two types of receptors does ACh bind?

Answer 20

1. nicotinic receptor
2. muscarinic receptors

Question 21

Nicotinic Receptor Mechanism

Answer 21

ACh opens

Question 22

What are the subtypes of nicotinic receptors?

Answer 22

• alpha and beta subunits
• Skeletal muscle (N1 or Nm)
• Autonomic ganglia (N2 or Ng)

Question 23

other ligand gated channels

Answer 23

Question 24

Muscarinic Receptors

Answer 24

• not channles
• assoc. with G-proteins
• 5 subtypes (m1-m5)

Question 25

m1,3,5 receptors function

Answer 25

Activate Phospholipase C through Gq ## Footnote PLC activation ---> increased IP3 --> increased intracellular Ca++ Increased intracellular Ca++ ---> Activation of Ca++-sensitive K+ & Cl- channels. * Generally, cause smooth muscle contraction

Question 26

m2 and m4 receptor function

Answer 26

1. Gi -coupled inhibition of adenylate cyclase 2. Gi -coupled activation of certain (e.g., GIRK) K+ channels ?? Sometimes you see these called** Gk** or **Go** coupled * Classic example will be M2 receptors in heart * Generally, have an inhibitory effect

Question 27

What are the three familes of Adrenergic Receptors?

Answer 27

sympathetic Nervous System * G-protein Association

Question 28

Adrenergic receptor are coupled to cellular processes through...?

Answer 28

G-proteins

Question 29

B-Adrenegeric receptors are coupled to which G protein? what is the end result?

Answer 29

* Gs, which stimulates cAMP which increases PKA act. * tend to relax smooth muscle

Question 30

alpha1 adrenergic receptor is couples to what G protein?

Answer 30

Gq, which activates PLC, which increases either 1. **IP3 and DAG** 2. **Ca2+ channels ** tend to **contract smooth muscle**

Question 31

alpha 2 adrenergic receptor

Answer 31

Gi -mediated inhibition of adenylate cyclase. * Decreased cAMP * Decreased PKA activity. Gi – activates K+ channels * Hyperpolarizes cell membranes * Classic example is presynaptic inhibition of neurons * tends to inhibit (i.e. pre-synaptic neurotransmitter release)

Question 32

Adrenergic Receptor Review

Answer 32