Signaling Receptors

Question 1

The ___ terminus of the G protein is extracellular.

Answer 1

N

Question 2

_______ stimulate enzymes, while ______ inactivate enzyme reaction.

Answer 2

Agonists; antagonists

Question 3

The _____ subunit of the G-protein receptor binds GTP in its active state.

Answer 3

alpha

Question 4

Cholera toxin turns the G-protein alpha subunit permanently ______.

Answer 4

off by disabling GTPase ability

Question 5

Pertussis ______ the G-protein.

Answer 5

inactivates (by locking in the inactive state)

Question 6

Which GPCRs inhibit adenylate cyclase? Which stimulate it?

Answer 6

GI and GS

Question 7

Name two beta-adrenergic receptor blockers.

Answer 7

Propranolol and metoprolol

Question 8

What is the normal pathway for beta-adrenergic receptor?

Answer 8

G-alpha stimulates adenylate cyclase, which activates PKA which raises [Ca].

Question 9

______ inhibits adenylate cyclase.

Answer 9

m2 muscarinic cholinergic receptors (Gi).

Question 10

Caffeine, theophyline, Milinirone, and Rolipram all inhibit ______.

Answer 10

phosphodiesterase

Question 11

Atropine is given to __________.

Answer 11

increase heart rate by antagonizing muscarinic receptors (they close potassium channels that hyperpolarize cells).

Question 12

GPCRs are removed from the cell membrane by binding to ________.

Answer 12

beta-arrestin