Week 7. Intracellular signalling pathway

Question 1

What are the common features of a signalling pathway?

Answer 1

• many different proteins
• includes ADP/ATP, GDP/GTP
• -> provide energy

Question 2

What is the function of a kinase?

Answer 2

catalyses phosphorylation

Question 3

What is the most common pathway for mediating endocrine responses?

Answer 3

Adenylyl cyclase 2nd messenger pathway

Question 4

What is a kinase?

Answer 4

protein enzyme

Question 5

What is the immediate action of the adenyl cyclase pathway?

Answer 5

1. Hormone (ligand) binds to G protein receptor on membrane.
2. Adenylyl cyclase activated
3. ATP is converted to cAMP.
4. cAMP stimulates cAMP dependant PKA to phosphorylate proteins –> enzyme activity changed

Question 6

Is the kinase energy dependant?

Answer 6

Yes, it requires ATP

Question 7

What is the second effect of the pathway?

Answer 7

alters binding activity of transcription factors using CREB protein, which binds DNA. This can regulate gene transcription, which regulates the amount of protein produced.

Question 8

What is the difference between thyroid hormone and insulin?

Answer 8

Thyroid hormone is intracellular, and binds in the cytosol. No signalling required.
Insulin is extracellular, and binds to the membrane. Signalling required.

Question 9

Which hormones bind to G protein coupled receptors?

Answer 9

TSH, adrenaline/noradrenaline, glucagon, GHRH