Signal transduction

Definition

The term signal transduction refers to a two-step process by which a signal outside the cell can induce a response inside the cell. The two steps are as follows:

1. A signaling molecule (outside the cell) activates a cell surface receptor located on the cell membrane (and hence capable of interacting with the molecule).
2. A messenger molecule transmits the signal from the cell membrane into the cell and elicit a physiological response within the cell.

The pathways by which this happens are termed signal transduction pathways.