Signal transduction is the process by which a cell responds to a signal, such as a hormone, neurotransmitter, or growth factor.
It converts the signal from outside the cell into a specific response inside the cell.
Here’s the mechanism explained:
1. Signal reception
A signaling molecule (like a hormone) binds to a receptor protein on the cell membrane or inside the cell.
- The receptor acts like a sensor that detects the signal.
2. Signal activation
When the receptor binds to the signal, it changes shape and becomes activated.
This activation triggers a series of chemical reactions inside the cell.
3. Signal transduction pathway
The activated receptor passes the message through a chain of molecules inside the cell (called second messengers).
Common second messengers include:
- cAMP (cyclic AMP)
- Calcium ions (Ca²⁺)
- IP₃ (inositol triphosphate)
These messengers amplify the signal so that even a small amount of hormone can produce a big effect.
4. Cellular response
The final step leads to a specific action in the cell, such as:
- Making or stopping the production of a protein
- Opening or closing ion channels
- Changing enzyme activity
- Altering gene expression
5. Signal termination
Once the job is done, the signal is switched off to prevent overreaction and keep the system balanced.
In short:
Signal transduction is how cells receive, process, and respond to signals.
It works through receptor activation, second messengers, and cellular responses, ensuring the right reaction happens at the right time.