 Homoserine is an intermediate in the biosynthesis of threonine, isoleucine, and methionine.The enzyme can be found in a monofunctional form, in some bacteria and yeast.Structural analysis of the yeast monofunctional enzyme indicates that the enzyme is a dimer composed of three distinct regions; an N-terminal nucleotide-binding domain, a short central dimerisation region, and a C-terminal catalytic domain.