Protein   activity   can  be
   regulated by
<P>
<lI> feedback  inhibition  when  the  product  of the metabolic pathway
inhibits activity of the first enzyme in the pathway.
Review:  <A ClAsS=MID Href="../../../med/Vid/Campbell8e/40_Animations/40_08NegativeFeedback_A.swf" oNClick="popurlt('../../../../med/Vid/Campbell8e/40_Animations/40_08NegativeFeedback_A.swf');txtcolor('trp_regulation1','gray');return false;" Id=trp_regulation1><iMg sRc="/images/shockwave.gif" aLt='' boRDer=0></A>
<lI> gene  regulation  when  the  genes  coding  for the enzyme are not
transcribed (expressed).