Wize AP Biology Textbook > Cell Communication

Second Messengers [short]

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Second Messengers
After receptors are activated by a ligand ("first messengers") and transmit that signal from the outside to the inside of the cell, the signal can be passed on to other (non-protein) molecules. 
This process is called signal transduction.
The molecules that carry on the message are called second messengers.
This often sets off a chain of events that is called a signaling pathway.
Photo by Yaneeporn / CC BY

Common types of second messengers are:
Calcium
Cyclic AMP (cAMP)
Inositol Triphosphate (IP3)
Photo by Takanori Nakane / CC BY

Second messengers:

A) Always cause phosphorylation of downstream molecules

B) The first event that leads to second messengers is the binding of a ligand to a receptor

C) They cannot be involved in signal transduction

D) ATP is a type of second messenger

I don't know