Question

Adenylyl cyclase and PI-PLCb are

Which of the following answers is incorrect?

a. both effectors in GPCRs’ signaling pathways

b. both produce secondary messengers when activated by the trimeric G protein-alpha subunit.

c. both inactivated when trimeric G protein-alpha subunit is hydrolyzing the GTP to GDP.

d. both activated by the activated trimeric G protein-alpha subunit.

e. both activated by the trimeric G protein-alpha subunit binding to GDP.

what is the major functional difference between GPCRs and RTKs?

a.RTKs can activate the Ras-MAP kinase pathway and GPCRs cannot.

b.GPCRs are a larger superfamily of receptors than RTKs.

c.GPCRs have more transmembrane domains then RTKs.

d.GPCRs are integral membrane proteins and RTKs are not.

e. RTKs are enzymes (tyrosine kinases) and GPCRs are not.

How is it possible that the activation of PKA in various tissues leads to such different responses in each tissue

a.The presence of various GPCR isoforms in each tissue

b.The presence of various PKA isoforms in each tissue

c.The different pace of cAMP degradation in each tissue

d.The presence of various G protein isoforms in each tissue

e.The presence of a different AKAP scaffold in each tissue

Answer 1

Answer for the first question : Option (e) - both activated by the trimeric G protein-alpha subunit binding to GDP.

Adenylyl cyclase and PI-PLCb both activated by the activation of alpha subunit by binding to GTP not GDP.

Adenylyl cyclase and PI-PLCb are common target of activated GPCRs. So, both are effectors of GPCRs.

Both of them produces secondary messengers when activated by the trimeric G Protein alpha subunit. Adenylyl cyclase produces cAMP from ATP. PI- PLCb produces IP3 and DAG.

Both become activated when alpha subunit binds to ATP and become inactivated when GTP hydrolyzes into GDP.

Both of them are activated by the activation of the alpha subunit of the G Protein.

So, Statement (a), (b), (c), (d) are not the right answer as these statements are correct and Option (e) is the right answer as it is incorrect.