Cell Signaling

Question 1

Beta Adrenergic Receptor

Answer 1

GPCR that binds epinephrine –> exchanges GDP for GTP –> laterally diffuses to adenylate cyclase –> formation of cAMP –> stimulation of protein kinase A

Question 2

GAPs

Answer 2

Stimulate intrinsic GTPase activity of GPCRs

Question 3

GEFs

Answer 3

Assists in GPCR exchange of GDP for GTP

Question 4

Visual Pathway Signaling

Answer 4

light stimulates transducin –> stimulates phosphodiesterase that converts cGMP to GMP and propagates visual signal via rhodopsin

Question 5

Phosphoionositide System

Answer 5

GPCR binds agonist –> translocates to phospholipase C –> hydrolyzes PIP2 to DAG and InsP3 –> stimulation of protein kinase C and ER release of calcium

Question 6

Insulin Receptor

Answer 6

insulin bids to 2 IR monomers that dimerize –> autophosphorylation of each other –> sarc domain recognizes phosphotyrosine and interacts with PI3K –> AKT activates PKC –> transmits GLUT4 receptors to surface for glucose uptake

also stimulates RAS/MAPK pathway for cell growth and survival; mutant RAS lack GTPase activity so stimulation goes on indefinitely

Question 7

Growth Factor Activation Pathway

Answer 7

Growth factor binds RTK –> recruits GEFs SOS and Grb2 to stimulate RAS –> stimulates kinase cascade leading to cell growth and proliferation

Question 8

mTORC1

Answer 8

Sensitive to rapamycin; regulates protein synthesis, lipid metabolism and autophagy via PI3K/ATK pathway

Question 9

mTORC2

Answer 9

Insensitive to rapamycin; involved in cytoskeleton, cell survival and metabolism via p53 and glucose pathways