^{Aside from being a proteinogenic amino acid, tyrosine has a special role by virtue of the phenol functionality. It occurs in proteins that are part of signal transduction processes. It functions as a receiver of phosphate groups that are transferred by way
of protein kinases (so-called receptor tyrosine kinases). Phosphorylation of the hydroxyl group changes the activity of the target protein.}

^{Medical use:
Tyrosine is a precursor to neurotransmitters and increases plasma neurotransmitter levels (particularly dopamine and norepinephrine)but has little if any effect on mood.The effect on mood is more noticeable in humans subjected to stressful conditions}N-Acetyl-L-tyrosine is an important fine chemical intermediate, widely used in medicine, pesticides, chemical industry and other fields

N-Acetyl-L-tyrosine is an important fine chemical intermediate, widely used in medicine, pesticides, chemical industry and other fields.