second messenger

noun

, Biochemistry.

1. any of various intracellular chemical substances, as cyclic AMP, that transmit and amplify the messages delivered by a first messenger to specific receptors on the cell surface.

second messenger

1. A molecule that relays messages in a cell from a receptor on a cell membrane to the final destination where an action within the cell is to take place. ( See signal transduction pathway .)

Word History and Origins

Origin of second messenger¹

First recorded in 1960–65