How much Glutamate is used to build proteins

[ndtb]

and how much of it is used as a neurotransmitter?

Of the alleged 50g a day produced by the body? How much of it is incorporated as a protein building block and how much remains free to act as a neurotransmitter?

Also I wonder how long does it last in it's free form before it is metabolized?

If you know, please share!

(Trying to decipher the information available about MSG, free Glutamate, bound Glutamate, protein incorporated Glutamate, etc.,)

Thanks!