Taurine (/ˈtɔːriːn/ ; IUPAC: 2-aminoethanesulfonic acid) is a naturally occurring organic compound with the chemical formula C2H7NO3S, and is a non-proteinogenic amino sulfonic acid widely distributed in mammalian tissues and organs. Structurally, by containing a sulfonic acid group instead of a carboxylic acid group, it is not involved in protein synthesis but is still usually referred to as an amino acid. As non-proteinogenic amino sulfonic acid, it is not encoded by the genetic code and is distinguished from the protein-building α-amino acids.