Threonine is an amino acid found in proteins. In mammals, threonine is an essential amino acid, meaning it must be present in the diet.

The hydroxy- and sulfur-containing amino acids are generally more hydrophilic than their aliphatic analogs.

Threonine's alcohol side group is a target for phosphorylation in proteins.

One Letter Code	Three Letter Code	Molecular Wt. (Daltons)	Genetic Code Codons
T	THR	101.11	ACU, ACC, ACA, ACG