Anti-GFUS antibodies are used in the immunodetection of the protein GDP-L-fucose synthase. In humans, the canonical protein has a reported length of 321 amino acid residues and a mass of 35.9 kDa. It is notably expressed in the testis, kidney, bronchus, breast, and adrenal gland. A member of the NAD(P)-dependent epimerase/dehydratase protein family, GFUS is known to catalyze the two-step NADP-dependent conversion of GDP-4-dehydro-6-deoxy-D-mannose to GDP-fucose, involving an epimerase and a reductase reaction. Synonyms for this target antigen include P35B, SDR4E1, TSTA3, 3-5 epimerase/4-reductase, GDP-4-keto-6-deoxy-D-mannose epimerase-reductase, and FX. GFUS gene orthologs have been reported in the mouse, rat, bovine, frog, chimpanzee and chicken species.