first messenger

first mes·sen·ger

a hormone that binds to a receptor on the cell surface and, in so doing, communicates with intracellular metabolic processes.

first messenger

A HORMONE or NEUROTRANSMITTER operating outside a cell and interacting with a cell membrane receptor. The second messenger operates within the cell.

first mes·sen·ger

(fĭrst mesĕn-jĕr)
Hormone that binds to a receptor on cell surface and, in so doing, communicates with intracellular metabolic processes.
References in classic literature ?
As another officer sped his horse after the first messenger, the general beamed upon the earth like a sun.
The easy way was to write to her, and send the letter, by the first messenger he could find, to the inn.
The brain's first messenger system (the Big Three Triangle) is a network of signaling molecules that bind receptors on the outside of cells.
We identified ATP as a novel first messenger for [GH.
ATP has a dual role as both an energy source for enzymatic reactions and as a first messenger for several classes of G protein-coupled receptors and ligand-gated ion channels.
IL12 isn't the first messenger molecule to raise the hope of a wonder drug.
The First Messenger, an old man who comes from Corinth with word that Polybus and Merope are dead and that the people of that city want Oedipus to return as their king.
Modi's emissaries were the first messengers of that hope.
And these genes may be genes that control rates of biosynthesis of important second and even first messengers.