34. Cell Signalling

Question 1

What is an example of paracrine signalling?

Answer 1

Somatostatin from pancreas acts locally

Question 2

How do T cells signal?

Answer 2

By plasma membrane-attached proteins which bind to receptors on adjacent target cell

Question 3

What are the four signal-transduction mechanisms?

Answer 3

Ligand-gated ion channels
G-protein-couples receptors
Kinase-linked receptors
Nuclear receptors

Question 4

What is a G-protein?

Answer 4

Trimeric signal-transducing proteins that bind GTP or GDP

Question 5

How does the G-protein create an intracellular response?

Answer 5

Ligand binding to a G-protein coupled receptor activates an associated G-protein which activates/inhibits a downstream enzyme to generate an intracellular second message

Question 6

How many regions do G-protein coupled receptors have?

Answer 6

7 membrane spanning regions

Question 7

Which receptor types act the fastest? Which act slowest?

Answer 7

Ion channels are fastest (ms), then G-protein (seconds), then kinase- and nuclear receptors (hours)