# How are signal transduction pathways turned off?

Oct 31, 2016

Signal transducing pathways are turned off using two mechanisms , down regulation and desensitisation.

#### Explanation:

Cells have two mechanisms for increasing their responsiveness to a hormone

Down regulation
It is the result of a decreased concentration of the receptor, fewer receptors means a smaller response to a signal.

Desensitisation
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