7. Effector Mechanisms Flashcards Preview

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Flashcards in 7. Effector Mechanisms Deck (23)
0

Define the term agonist

Chemical that binds to a receptor and activates it

1

Define the term antagonist

Bonds to a receptor and blocks it

2

Describe the structure of a GPCR receptor

Single polypeptide chain
7 transmembrane domains
Extracellular N terminal
Intracellular C terminal

3

What regions can act as a binding site on GPCRs?

2-3 transmembrane domains
N terminal region

4

Describe the mechanism of how a GPCR works

Ligand binds - causes conformational change
Activated GPCR interacts with G protein
This causes GDP for GTP exchange of the alpha subunit
The alpha beta gamma subunits dissociate into alpha GTP and beta gamma subunits
Each can interact with effector proteins
Interaction lasts until the alpha subunit GTPase hydrolysis GTP into GDP and the subunits reform the complex

5

What is the Gs effector?

Stimulating adenyl cyclase

6

What is the Gi effector?

Inhibiting adenyl cyclase

7

What is the Gq effector?

Stimulates phospholipase c

8

What is the Gt effector?

Stimulates Cyclic GMP phosphodiesterase

9

What G protein do Beta adrenoreceptors couple with?

Gs

10

What G protein do alpha 1 adrenoreceptors couple with?

Gq

11

What G protein do alpha 2 adrenoreceptors couple with?

Gi

12

What G protein does rhodopsin couple with?

Gt

13

What G protein does M2/M4 receptors couple with?

Gi

14

What G proteins do M1/M3 couple with?

Gq

15

What is the "ligand" for rhodopsin?

Light

16

What toxin produces cholera?

Cholera toxin, CTx

17

What toxin produces whooping cough?

Pertussis toxin, PTx

18

How does cholera toxin affect G proteins?

Eliminates GTPase activity of Gs therefore Gs becomes irreversibly activated

19

How does Pertussis toxin affect proteins?

It interferes with GDP/GTP exchange on Gi therefore Gi becomes irreversibly inactivated

20

What does adenyl cyclase interact with?

Protein kinase A, activates the catalytic subunits allowing them to phosphorylated other proteins

21

What does phospholipase C interact with?

PIP2

22

In heart muscle, what does an increase in Ca2+ influx lead to?

Positive inotropy (increased force of contraction)