1. Lecture 9: Cell Communication
Bio 93: DNA to Organisms
Lecture 9: Cell Communication
What happens when you get scared?

2. Lecture 9: Learning Objectives
9.1 – Explain how cell signaling pathways proceed via the steps of reception, transduction, and response 9.2 – Explain the steps of the epinephrine-GPCR pathway 9.3 – Predict what might happen to cellular pathways if they are interrupted

3. Lecture 9: Key terms Gap junction Protein phosphatase
Paracrine signaling
Phosphorylation
Synaptic signaling
Dephosphorylation
Endocrine signaling
Second messenger
Hormones
Cyclic AMP (cAMP)
Reception
Adenylyl cyclase
Transduction
Epinephrine
Response
Glycogenolysis
Signal transduction pathway
Protein kinase A
Ligand
Phosphorylase kinase
G protein-coupled receptor (GPCR)
Glycogen phosphorylase
Intracellular receptor
Protein kinase

4. What happens when you get scared?
9.1
Epinephrine
What type of signaling pathway is this?
How does epinephrine get to the muscles of the body?

5. Epinephrine induces glycogenolysis
In muscle cells
How does this happen?
Epinephrine
Glucose
9.2

6. 1 2 Explain what is going on in this figure to your neighbor
EXTRACELLULAR FLUID
CYTOPLASM
Plasma membrane 1
Reception 2
Transduction 3
Response
Receptor
Glycogen-
olysis 1 2 3
Relay molecules
Epinephrine
How is a signaling pathway with testosterone different?
9.1
Can you draw the detailed pathway for how epinephrine induces glycogenolysis? 2
9.2

7. Cytoplasm of a muscle cell
Extracellular fluid
Cytoplasm of a muscle cell

8. Glycogen phosphorylase
Adenylyl cyclase
GPCR
Glycogen phosphorylase
GTP
cAMP
Epinephrine
Glucose
ATP
GDP
Protein kinase A
G protein
Phosphorylase kinase
Glycogen

9. 2
What is the correct order of proteins that the signal passes through? (not all proteins are listed)
A – glycogen phosphorylase B – adenylyl cyclase C – GPCR D – Protein kinase A E – cAMP
9.2

10. G protein coupled receptor (GPCR) structure
GPCRs structure:
Receptor is a multipass protein, crossing membrane 7 times with specific orientation to form cylindrical structure with deep ligand binding site at center
GPCRs interact with G proteins associated with the cytosolic leaflet of the membrane

11. What do kinases do?
By adding a phopsphate group to a protein, the kinase induces a conformational change in the protein, resulting in a change in the proteins function.
Bio 93 (Summer 2017), Copyright © 2017, Dr. Salme Taagepera. All rights reserved.

12. 2 What would NOT happen if protein kinase A was blocked by a drug?
A – cAMP would be produced from ATP
B – Intracellular [glucose] would increase
C – Epinephrine would bind to the GPCR
D – The G protein would diffuse in the membrane
Figure 11.6 on page 224 2
9.2
9.3

13. Question: How does epinephrine affect skeletal muscle metabolism?
Hypothesis: Epinephrine increases glycogenolysis
Experiment: Injected epinephrine or saline (control) into rat hindlimb musculature, measured many parameters over time
Measured:
Phosphorylase kinase activity
Protein kinase A activity
Cellular glucose concentration
Glycogen synthase activity
9.2

14. 9.2
What will happen to these parameters for control (saline) and epinephrine injections? 3
Protein kinase A activity
[Glucose]
Time (minutes of infusion)
Time (minutes of infusion)
Phosphorylase kinase activity
Time (minutes of infusion)
glucose

15. 9.2
What will happen to these parameters for control (saline) and epinephrine injections? 3
Glycogen synthase activity
Time (minutes of infusion)
glucose

16. What results do you think they observed for glycogen synthase activity?
Red – saline
Blue – epinephrine B 3
9.2

17. Other effects of adrenaline…
Allergic reactions can cause body to go into anaphylactic shock:
decreased heart rate
dilated blood vessels
closed airways
Epinephrine:
increases heart rate
constricts blood vessels
opens the airways
This is why Epi pens work!
Bio 93 (Summer 2017), Copyright © 2017, Dr. Salme Taagepera. All rights reserved.