activator

from WordNet (r) 3.0 (2006)

activator
    n 1: (biology) any agency bringing about activation; a molecule
         that increases the activity of an enzyme or a protein that
         increases the production of a gene product in DNA
         transcription [ant: {inhibitor}]

from The Collaborative International Dictionary of English v.0.48

activator \activator\ n.
   1. any agency bringing about activation; (Biol.) a molecule
      that increases the activity of an enzyme or a protein that
      increases the production of a gene product in DNA
      transcription.
      [WordNet 1.5]

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