Receptor Transduction Mechanisms

Question 1

What is signal transduction?

Answer 1

Converting information encoded by external signal into biological effect

Question 2

Which receptor type is the target for most therapeutic drugs?

Answer 2

GPCRs

Question 3

What are the three subunits of a heterotrimeric G-protein?

Answer 3

Alpha
Beta
Gamma

Question 4

What is responsible for anchoring the alpha and beta-gamma subunits of a G-protein to the plasma membrane?

Answer 4

Fatty acyl tails

Question 5

Ligand binding to a GPCR causes a conformational change in which part of the receptor?

Answer 5

Third intracellular loop

Question 6

Which type of protein can accelerate the GTPase activity of the alpha-subunit of a G protein?

Answer 6

GTPase-activating proteins (GAPs)

Question 7

What are the 4 main G-protein families and their functions?

Answer 7

Go - activates K+ channels + stimulates PLC
Gs - activates adenylyl cyclase
Gi - inhibits adenylyl cyclase
Gq - activates K+ channels + stimulates PLC

Question 8

Which G-protein is coupled with beta-adrenoceptors?

Answer 8

Gs

Question 9

Which G-protein is coupled with mu/delta opiate receptors?

Answer 9

Gi + Go

Question 10

Which G-protein is coupled with M1 receptors?

Answer 10

Gq

Question 11

Phosphorylated tyrosine residues in the kinase domain of RTKs act as docking sites for which protein domains?

Answer 11

Src (SH2 + SH3)

Question 12

What are the names of the two stages of steroid action via an intracellular receptor, and what do these stages involve?

Answer 12

Early primary response:
Steroid displaces inhibitory protein complex blocking receptor
Hormone-receptor complex activates primary response genes
Multiple primary response proteins synthesised

Delayed secondary response:
One primary response protein inhibits primary response gene expression
One primary response protein activates multiple secondary response genes
Multiple secondary response proteins synthesised