Question

Explain in as much detail as possible, how intracellular signaling leads to a signal amplification.

Answer 1

Amplification of a signal is initiated by the binding of a ligand to its receptor. Then the recepto will stimulate the intracellular enzymes. The intracellular enzymes propagate and amplify the signal initiated by ligand binding on receptor and it serve as downstream signaling elements

For example, consider the downstream signaling of epinephrine

The binding of a signal molecule on the cell surface receptor activate a number of G proteins. These G proteins can activate adenyl cyclase, each adenyl cyclase then induce the production of huge number of cAMP messengers. The production of a large number of cAMP or second messenger itself is a mechanism to amplify the
signal, which is originally generated. In the next step, a large number of PKA will be activated by each cAMP molecules. These each PKA catalytic subunit are capable of phosphorylating a large number of phosphorylase
kinase molecules. These phosphorylase kinase molecules then phosphorylate a large number of glycogen phosphorylase molecules. Action of these glycogen phosphorylase molecules catalyses the formation of a large number of glucose phosphates. This cause the mobilization of a large number of glucose within the cellI. Thus the signal created by the binding of a single ligand molecule to the receptor can be amplified many times more.