Second messenger

Definition

A second messenger is a molecule that relays signals received at receptors on the cell surface to target molecules in the cytosol or nucleus. They amplify the strength of the signal from a first messenger, such as a hormone, to initiate a physiological response.

Related terms

Hormone: Chemical substances produced by glands that regulate bodily functions by sending messages through the bloodstream to specific cells.

Receptor:

A protein molecule embedded in either the outer membrane or inside of a cell that binds to specific molecules like hormones, enabling them to relay messages into the cell.

Signal Transduction: The process by which a chemical or physical signal is transmitted through a cell as a series of molecular events, most commonly involving changes in levels of second messengers