Signal Transduction

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Signal Transduction

1. Norepinephrine/epinephrine bind to the g-protein (alpha-2) receptor

resulting in a confirmational change.

2. This change causes the alpha subunit of the receptor to bind with

andenlyl cyclase. Before binding, adenlyl cyclase is an inactivated enzyme,

once the alpha subunit binds with adenlyl cyclase it becomes activated.

3. The activated adenlyl cyclase can then convert ATP into cAMP. (cAMP is a

secondary messenger)

4. cAMP targets protein kinase. (protein kinase is made up of 2 regulatory

subunits and 2 catalytic subunits, when these subunits are attached to one

another protein kinase is inactivated.)

5. cAMP binds to the regulatory portions of protein kinase and causes

release of the catalytic portions.

6. These catalytic portions then result in a cascade of energy, they become

activated when they pick up ATP.

7. The activated form of protein kinase then causes protein

phosphorylation.

8. Response is produced.

Phospholipase C Pathway

1.

Norepinephrine/epinephrine bind to

the G-protein (alpha-1) receptor resulting in a confirmational change.

2.

G subunit binds with phospholipase C.

3.

Phospholipase C causes the splitting

of PIP2 into IP3 and DAG.

4.

IP3 causes the release of calcium

ions (Ca2+) from endoplasmic reticulum.

5.

DAG activates protein kinase C along

with the Ca2+/calmodulin complex.

6.

Protein kinase C phosphorylates

proteins that go on to generate a response.

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