Breakdown of glycogen to glucose

Fischer and Krebs discovered how the breakdown of glycogen to glucose is controlled in the skeletal muscles, so that energy supply matches energy demand.

1. Acetylcholine is released from a motor nerve. This causes an entry of calcium into the muscle cell.

2. Calcium activates phosphorylase kinase - the first protein kinase discovered by Fischer and Krebs.

3. Phosphorylase kinase phosphorylates phosphorylase, which is activated

4. Glycogen is broken to glucose. This is used to generate ATP

5. The muscle works and requires energy in the form of ATP

6. The muscle contains muscle cells

7. Contractile proteins in the muscle are activated by calcium