Mol Lecture #38

Question 1

cAMP receptor- response pathway

Answer 1

• One example of GPCR based signalling
• Bind ligands that are very diverse (class of receptors are diverse)
• Receptor undergoes a conformational change, and binds a GTPase
• Later: cAMP is an example of second messenger
• Response: Protein Kinase A

Question 2

Glucagon (protein hormone)

NOTE: BOTH receptor signalling and protein hormone signalling change GE

Answer 2

• Hormone released by the pancreas that helps increase blood glucose (opposes insulin activity).
• Acts on multiple cell types.
• Fits inside the basket of the 7 transmembrane region
• PKA causes inhibitory phosphorylation of glycogen synthase to prevent glycogen formation (prevents glucose as being stored as glycogen)
• PKA induces inhibitory phosphorylation of Acetyl-carboxylase leading to increased acetyl-CoA production from fatty acids. (running it back up to produce glucose)

Question 3

What does Glucagon do?

Answer 3

• It causes phosphorylation of glycolytic enzymes such as phosphofructokinase to inhibit and reduce glucose oxidation (what’s mediating this: Protein kinase A- at the bottom of the pathway)

Question 4

Intracellular Receptors for hydrophobic ligands (Steroid hormone receptors)

Answer 4

• The receptor ends up doing the signal transduction and mediating the response
• Now it functions as a transcription factor

Question 5

Integration of signaling pathways

Answer 5

• Cells integrate information to make decision