FAD-linked sulfhydryl oxidase ALR, also known as GFER, belongs to the Erv1/ALR family of proteins. This family can be found in higher and lower eukaryotes. GFER is a hepatotrophic growth factor and flavin-linked sulfhydryl oxidase expressed in various tissues. Also, GFER induces the expression of S-adenosylmethionine decarboxyl-ase and ornithine decarboxylases (ODC), which each play an important role in the synthesis of polyamines. Recombinant human GFER protein, fused to His-tag at N-terminus, was expressed in E.coli and purified by using conventional chromatography techniques.