For 10 points, name this amino acid whose monoÂ·sodium salt is responsible for the flavor of umami.
Alpha tubulin undergoes a post-translational modification in which chains containing four to six of this molecule are added near its C-terminus. In plants, algae, and bacteria, the starting point for porphyrin biosynthesis is the production of aminoÂ·levuÂ·linÂ·ic acid from this molecule. Flux through the urea cycle is regulated by allosteric activation of CPS I by an N-acetyl derivative of this molecule. Vitamin K causes many proteins in the clotting pathway to undergo carboxylation at these residues. One of this compound's receptors is blocked by a magnesium atom which must be displaced for long-term potentiation to occur. A PLP-dependent enzyme decarboxylates this molecule to form the inhibitory neurotransmitter GABA  ("gabba") . For 10 points, name this amino acid whose monoÂ·sodium salt is responsible for the flavor of umami.
Alpha tubulin undergoes a post-translational modification in which chains containing four to six of this molecule are added near its C-terminus.
glutamate  [or  Glu ; or  E ]