tyrosine

An aromatic amino acid that is obtained from the hydrolysis of proteins and is a precursor of epinephrine, thyroxine, melanin and other important compounds. It is needed to make melanin (the pigment in cats skin and hair). If a cat (organism) can't make tyrosine then it can't make melanin. i.e., Albino. Overly active tyrosine can produce areas of highly pigmented skin/hair or result in melanomas. See Tyrosinase.

SOURCE: cat-world.com.au