Signal Transduction

Question 1

what does G protein type Gαq (or Gq) stimulate?

Answer 1

phospholipase C

Question 2

what does G protein type Gs do?

Answer 2

• stimulates adenylate cyclase

- increases cAMP

Question 3

what does G protein type Gi do?

Answer 3

• inhibits adenylate cyclase

- decreases cAMP

Question 4

how is cAMP synthesised?

Answer 4

within cells from ATP by enzyme adenylate cyclase

Question 5

how is cAMP degraded?

Answer 5

by enzyme cAMP phosphodiesterase

Question 6

what is cholera toxin?

Answer 6

• Oligomeric complex which after cleavage becomes active and enters intestinal epithelial cells to stimulate Gαs
• The overstimulation of cAMP production results in a release of water and ions including Na+, K+, Cl- and HCO3- into the lumen of the small intestine

Question 7

what toxin acts in reverse to cholera toxin?

Answer 7

Pertussis toxin: acts in the reverse manner inhibiting Gαi to increase cAMP production in lung epithelia

Question 8

what protein activates the MAPK (mitogen-activated protein kinase) pathway?

Answer 8

Ras

Question 9

what type of cancer is associated with EGFR overexpression?

Answer 9

• colorectal cancer
• pancreatic cancer
• lung cancer
• non-small cell lung cancer

Question 10

what is EGFR?

Answer 10

• epidermal growth factor receptor

- RTK activated by TGFα (transforming growth factor alpha)