Tyrosine is an amino acid that is synthesized by your body and also acquired from sources of dietary protein. Like all amino acids, tyrosine is a building block of proteins, which are vital components of virtually all molecular biological processes. In addition, tyrosine is a major precursor for several neurotransmitters. Because of its role in neural stimulation, tyrosine may directly affect processes in the brain, including cognitive function and mood.
Role in Proteins
Tyrosine is an aromatic amino acid that is synthesized in your body from another amino acid called phenylalanine. Structurally, tyrosine plays an important role in proteins and enzymes, often on the surface or at the molecular binding sites. Tyrosine also can be modified to change the function or activity of a particular protein that can lead to cell communication, or cell signaling. According to a report in the June 2010 issue of the journal “Cell,” mutations that disrupt tyrosine-facilitated cell signaling may contribute to some diseases, including cancer.
When tyrosine is not incorporated into the structure of proteins, it remains a free amino acid in the body. These residues can then be used as building blocks for other important molecules. In the brain, tyrosine is used to synthesize a class of neurotransmitters known as catecholamines, which includes epinephrine, norepinephrine and dopamine. Catecholamines are important stimulators of mood and feelings of well-being, which may be improved with enhanced amino acid consumption. According to a review published in the June 2007 issue of the “Journal of Nutrition,” adequate consumption of dietary proteins leads to an increase in free tyrosine concentrations in the brain, which correlates to an increase in catecholamine production.
Tyrosine is important for the production of the thyroid hormones T3 and T4. Your thyroid gland is responsible for releasing these hormones to stimulate metabolic activity in your cells and tissues. According to the University of Maryland Medical Center, tyrosine supplementation is sometimes used to treat individuals suffering from hypothyroidism, or underactive thyroid, in an attempt to increase the production of thyroid hormones.
Tyrosine is the major chemical substrate for the synthesis of melanin, which is the pigment in your skin, eyes and hair. Specialized skin cells make melanin by oxidizing tyrosine with an enzyme called tyrosinase. Hereditary defects in the gene that encodes tyrosinase leads to a disorder known as albinism. People suffering from albinism cannot make melanin and do not typically have any pigment in their hair, skin and eyes.
- “Cell”; Cell Signaling by Receptor Tyrosine Kinases; Mark A. Lemmon and Joseph Schlessinger;June 2010
- “Journal of Nutrition”; Tyrosine, Phenylalanine, and Catecholamine Synthesis and Function in the Brain; John D. Fernstrom and Madelyn H. Fernstrom; June 2007
- Maryland Medical Center; Hypothyroidism; March 2010
- Encyclopedia of Children's Health: Albinism