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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:
  1. Calcium
  2. Cyclic AMP (cAMP)
  3. Inositol Triphosphate (IP3)
Photo by Takanori Nakane / CC BY

Second messengers: