High Yield GPCR Signaling

Question 1

What does a Gs-GPCR do?

Answer 1

Stimulates adenylate cyclase

Question 2

What does a Gi-GPCR do?

Answer 2

Inhibits adenylate cyclase

Question 3

What does a Gt-GPCR do?

Answer 3

Stimulates cGMP phosphodiesterase

Question 4

What does a Gq-GPCR do?

Answer 4

Activates phospholipase C

Question 5

What is the mechanism for a Gs-GPCR post GTP binding to the alpha subunit?

Answer 5

Activates AC, which uses ATP to make cAMP, which activates PKA, who then goes on to phosphorylate target proteins to alter their activity

Question 6

What is the mechanism for a Gi-GPCR post GTP binding to the alpha subunit?

Answer 6

Inhibits AC, so cAMP is not produced and PKA is not activated

Question 7

What is the mechanism for a Gt-GPCR post GTP binding to the alpha subunit?

Answer 7

Activates cGMP phosphodiesterase that turns cGMP into 5’-GMP

Question 8

What is the mechanism for a Gq-GPCR post GTP binding to the alpha subunit?

Answer 8

Activates PLC (phospholipase C) to cleave PIP2 into IP3 and DAG

IP3 releases Ca2+ from the ER, which binds to the calmodulin complex, which then activates proteins

DAG activates PKC (phosphokinase C), which then leads to the phosphorylation of target proteins to alter their activites

Question 9

What is the mechanism in receptor tyrosine kinases?

Answer 9

Signal binds to ECD causing receptor to dimerize which leads to autophosphorylation of tyrosine residues; phosphotyrosine recognized and bound by adapter and docking proteins, which goes on to activate downstream signaling pathways that are RAS dependent or independent, leading to a change in gene transcription and protein activity

• RAS-dependent = MAPK family*
• RAS-independent = different kinases*