Signal Transduction

We read a lot about inhibitors, activators, agonists, antagonists which modulate (adjust/alter) enzyme or cell-receptor function and thus reducing/preventing the illness. 

For example, kinase inhibitors as cancer theraeupatics;  PPAR agonists as antidiabetic agents.

But the story doesn’t end when an inhibitor or agonist binds to an enzyme or cell-receptor, respectively.  These inhibitors or agonists do not directly (in a single step) affect the illness.  There are several intermediary steps (cascade of events) after the initial binding which bring about the finally observed biological response.  Agonist/Inhibitor binds to cell receptor (first step, called reception) which will send signals within the cells, and this signal is passed (transduction) to the necessary location via several helping hands (say enzymes).  At last the response is observed.  Let me show a pictorial representation of this explanation.

Synthetic organic chemists can correlate the cascade of events which I mentioned earlier to cascade reactions in organic synthesis. 

Let us imagine ‘+’ charge as signal.  Now this signal has to reach from carbon circled in red to the carbon circled in blue of compound 1.  Compound 1 can be imagined as a cell receptor in inactive state.  Once TFA is added (imagine it to be an agonist), ‘+’ signal is generated.  Now this ‘+’ signal has to reach the final destination i.e. to the carbon circled in blue of compound 1.  By the help of several unsaturated functionalities both double and triple bonds (helping enzymes which facilitate transfer of signal) circled in blue in compound 2, ‘+’ signal reaches its destination.  Formation of compound 4 via compound 3 can be viewed as the final response of the signal.