Question

2a. What class of receptor is the insulin receptor?

b. How is the insulin receptor different than other receptors in this class?

3. Describe the steps between the binding of an insulin molecule at the surface of a target cell and the activation of the effector PI3K. How does insulin signaling lead to an increase in glucose uptake by cells?

4. How is insulin signaling altered in Type 2 diabetes?

5. What is the main goal of modern scientific research in Mechanical stress and insulin sensitivity?

6. Scientific studies use Drosophila (fruit flies) as a model organism to study insulin signaling. How is insulin signaling in flies similar to and different than insulin signaling in humans?

7. How did the researchers directly test the effect of mechanical stress/movement in the flies? Do you think this was a good mimic of a sedentary lifestyle in humans?

8. Which factors were required for transmitting the mechanical stress to the insulin signaling pathway?

9. Draw a model/schematic to describe the connection between mechanical stress and insulin signaling.

Answer 1

2.(a) Insulin receptor is a Receptor Tyrosine Kinase.

(b) Insulin receptor consisting of two alpha and two beta subunit form a heterotetramer linked through disulfide bonds. Where other Receptor belong to this group having one subunit, when ligand coming then this receptors form homodimer.

3. Increase of glucose uptake by insulin signalling :

- insulin binds to the receptor that activate IRS1.

- Then PI3K is activated by IRS1.

- Then activating of PDK1 is occured and this PDK1 activate both PKC and AKt which further activate TBC1D1 and TBC1D4.

- These form the GLUT4 vesicle and this vesicle fused to

Plasma membrane and liberate the GLUT4. It is the

Channel for glucose uptake. Thereafter glucose enter into

the cell by the GLUT4 .