Serine is synthesized from glycine and helps produce cysteine in the body from homocysteine.
It is one of three amino acids that is usually phosphorylated during cell signaling in eukaryotes (Wikipedia). Phosphorylated serine residues are referred to as phosphoserine. Serine proteases are a common type of protease. Serine has sugar-producing qualities and is very reactive in the body. It is highly concentrated in all cell membranes, helping manufacture immunoglobulins and antibodies.
Serine can be made in the body from either glycine or threonine, but its production is dependent on sufficient levels of vitamin B3, vitamin B6 and folic acid.
Serine is crucial in metabolism because it participates in the biosynthesis of purines and pyrimidines, cysteine, tryptophan (in bacteria), in the formation of cell membranes and in creatine synthesis and absorption.
Tryptophan is an amino acid the body uses to manufacture serotonin, a brain chemical. Serotonin levels play a key role in the regulation of mood, appetite, sexual behavior and aggression.
Creatine is an energy source used in the body to develop strength and stimulate muscle growth. It helps build and maintain all the muscles in the body, including the heart.
Serine is an integral component of brain proteins and nerve sheaths, important in the production of cell membranes and in muscle tissue synthesis. It helps make the immunoglobulins and antibodies that support a strong immune system.
Serine is also a constituent of phospholipids that help seal in moisture. It is included as a natural moisturizing agent in numerous skin care products.