Homoserine kinase is part of the threonine biosynthetic pathway.Homoserine kinase is a member of the GHMP kinases (Galactokinase, Homoserine kinase, Mevalonate kinase, Phosphomevalonate kinase) and shares with them an amino-terminal domain probably related to ATP binding.P.aeruginosa homoserine kinase seems not to be homologous (see PROSITE:PDOC0054) [Amino acid biosynthesis, Aspartate family]