Receptors of Growth Factors and Cytokines / Ca+ Metabolism

Question 1

What does phospholipase C activation lead to?

Answer 1

production of inositol triphosphate

→ activates protein kinase C

production of diacylglycerol

→releases Ca²⁺ from the ER

Question 2

What is a protein that can bind calcium and mediate further targets?

Answer 2

calmodium Ca²⁺→ cam kinases

Question 3

What is the signaling mechanism of inositol trisphophate/diacylglycerol?

Answer 3

1. signal moleculae activates G protein
2. G protein is activated GTP and it’s alpha subunit dissosociates from the beta and gamma subunit
3. activates phospholipase
4. activates IP3 and diacylgylcerol

Question 4

What two effector mechanisms can the Ca²⁺ signal regulate?

Answer 4

1. Dedicated CaM kinases
2. Multifunctional CaM kinases

Question 5

What are examples of dedicated CaM kinases?

Answer 5

• MLCK (Myosin light chain kinase)
• PhosK
• CaMKIII

Question 6

What are the functions of G_{<strong>12/13 </strong>}proteins?W

Answer 6

• activate Rho small G proteins
• cause activation of Rho Kinase

Question 7

What is the function of the alpha subunit of G_12/13?

Answer 7

activate the Rho family of G proteins

Question 8

What are adrenergic receptors?

Answer 8

a class of G protein-coupled receptors that are targets of the catecholamines, especially norepinephrine and epinephrine

Question 9

What are the types of plasma membrane receptors?

Answer 9

1. G protein coupled receptors
2. Ion channel receptors
3. Receptors with enzyme activity

→Tyrosine kinase receptors

→ Guanylyl cyclase receptors

4. Enzyme activity-linked receptors

Question 10

What are the different receptors that bind epinephrin/ norepinephrin?

Answer 10

alpha 1 & 2

beta 1-3

Question 11

What is the affinity, G protein, signal and example of the alpha subunits that are sensitive to catecholamine

Answer 11

Alpha 1

sensitivity: NE > E

G protein: G_q/11

signaling: phosphokinase C, Ca²⁺

example: smooth muscle cell

Alpha 2

sensitivity: NE > E

G-protein: G_i/o

signaling: cAMP decreases, K⁺ increases, Ca²⁺ decreases

example: presymatric

Question 12

What is the affinity, G protein, signaling and example of the beta subunits that are sensitive to catecholamine

Answer 12

beta 1

affinity: NE - E

example: cardiac

beta 2

affinity: NE << E

example: smooth muscle

beta 3

affinity: NE > E

example: smooth muscle

*all beta subunits have the G_{<strong>s</strong>} protein and the signaling has the result of increased cAMP*

Question 13

What are two types of acetylcholine receptors?

Answer 13

• ionotropic
• metabotropic

Question 14

What are the two different ion channel receptors?

Answer 14

muscle type

→ inhibitor: curae

neural type

→ inhibitor:

Question 15

What is ionotrpic?

Answer 15

nicotine acetylcholine receptor

Question 16

What is metabotropic? inhibitor?

Answer 16

muscarinic ACH

inhibited by: atroprine

Question 17

What are the different muscarinic receptors and what G protein do they activate? What are the effects?

Answer 17

M₁, M_3, M₅ ⇒ G_{<span>q/11 </span>} ⇒ Ca ²⁺, PK-C

M₂, M₄ ⇒ G_{i/o<span> </span>} ⇒ decreased cAMP, decreased Ca²⁺, increased K⁺