Week 3 cell signaling

Question 1

What is the stimulatory pathway of GPCR and what does it stimulate?

Answer 1

Gs stimulates plasma membrane adenylyl cyclases which increases cAMP that stimulates phosphyrlation of target proteins by protein kinase (PKA)

Question 2

Which cell signaling pathway releases glucose from the liver? This is done to counteract _________

Answer 2

Gs coupled hormones (glucagon and norepinephrine) can trigger stimulatory even that breaks down glycogen to glucose, stops glycogen synthesis (in nucleus) to counteract hypoglycemia.

Question 3

The cholera toxin inhibits activity of ________ which _________ PKA activity that acts on the _________ channel causing Cl to leave the cell resulting in diarrhea.

Answer 3

Cholera inhibits activity of Galpha-GTPase, it cannot turn itself off, this overstimulates PKA activity that acts on the CFTR channel causing Cl to leave the cell resulting in diarrhea.

Question 4

cAMP is an example of a ______________

Answer 4

Second messenger.

Question 5

G i/o is the target of which disease that turns this pathway off?

Answer 5

Pertussis.

Question 6

Which pathway inhibits most adenylyl cyclases which ______ the level of cellular cAMP?

Answer 6

Gi inhibits most ACs decreasing cellular cAMP response.

Question 7

Which pathways activate PKC?

Answer 7

GPCR (Gq) or TKR can activate PLC to cleave PIP2 to DAG or IP3.

1) PIP2 —-> DAG –> PKC
2) PIP2 —-> IP3 —> IP3R on endoplasmic reticulum —> Ca2+ released —-> PKC activated.

Question 8

GAP __________ (activates/inactivates) Ras while GEP ____________(activates/inactivates) Ras.

Answer 8

GAP inactivates (GTPase Activating Protein) Ras while GEP (GTP Exchange Protein) inactivates Ras.