How are signal transduction pathways turned off?
Signal transducing pathways are turned off using two mechanisms , down regulation and desensitisation.
Cells have two mechanisms for increasing their responsiveness to a hormone
It is the result of a decreased concentration of the receptor, fewer receptors means a smaller response to a signal.
It is the result of decrease in the cellular response to a second messenger.
The most obvious method for turning off a signal is the dissociation of the ligand from the receptor. Ligand dissociation can be induced (a cellular process),or can occur due to a decrease in the circulating ligand concentration.
Most second messengers have short half lives within the cell and therefore when the hormone dissociates , the second messenger levels decrease , terminating the signal