G Proteins and Signal Transduction
- Reception: the G protein is inactive if the first messenger (ligand) does not bind to the G-protein coupled receptor. Once the ligand binds to the receptor, the receptor becomes activated and changes shape which causes GTP to replace GDP - the G protein is now activated
- Transduction: The protein binds to the enzyme which causes the enzyme to trigger another activity with the second messenger (amplification - how one activity can trigger many things to happen)
- Response: the second messenger can now influence the cell and elicit the intended response
The G-Protein is reusable. Once it leaves the enzyme, the enzyme goes back to normal and the G-protein goes back to where it was on the receptor.