Riboswitch

thumb|A 3D representation of the lysine riboswitch (Protein Data Bank|PDB code:3DIL, orange and blue tubes) bound to lysine (shown as grey, red and blue spheres in the upper middle of the structure) In molecular biology, a riboswitch is a regulatory segment of a messenger RNA molecule that binds a small molecule, resulting in a change in production of the proteins encoded by the mRNA. Thus, an mRNA that contains a riboswitch is directly involved in regulating its own activity, in response to the concentrations of its effector molecule. The discovery that modern organisms use RNA to bind small