This enzyme belongs to the family of lyases, specifically those carbon-oxygen lyases acting on phosphates. The systematic name of this enzyme class is O-phospho-L-homoserine phosphate-lyase (adding water L-threonine-forming). Other names in common use include threonine synthetase, and O-phospho-L-homoserine phospho-lyase (adding water). This enzyme participates in glycine, serine and threonine metabolism and vitamin B6 metabolism. It employs one cofactor, pyridoxal phosphate.