Serine This amino acid is a precursor to the neurotransmitter glycine and is also involved in the manufacture of the amino acid cysteine. Serine is a neurotransmitter in its own right, reducing the excitability of nerves of the spine as well as a major component of important brain substances.

Serine and cell membranes
One of serine's more vital functions is as a component vital to cell membrane structure. The cell membrane is the thin "skin" which encloses and protects the contents of the cell. It regulates the entry and exit of the various chemicals the cell needs or excretes. The cell membrane is made of fats and proteins and has complex chemical reactions occurring within it therefore the cell membrane's structure, flexibility and integrity must be maintained to keep the body healthy It is important that all the correct substances used in the cell membrane are available, including serine.