Signal amplification.
<P>
   Epinephrine  acts  through  a  G-protein-linked receptor to activate a
   succession of relay molecules, including the second messenger cAMP.
<P>
   This amplifies the signal: one receptor protein can activate about 100
   molecules of G protein.
<P>
   Each  enzyme  in  the  cascade  can  act on many molecules of the next
   molecule,  resulting  in  a  100  million  -fold  amplification in the
   response.
<P>
   Review:  <A ClAsS=MID Href="../../../med/Vid/Raven7e/signal_amplification.swf" oNClick="popurlt('../../../../med/Vid/Raven7e/signal_amplification.swf');txtcolor('epinephrine1','gray');return false;" Id=epinephrine1><iMg sRc="/images/shockwave.gif" aLt='' boRDer=0></A>