UDP-glucose 4-epimerase

The enzyme UDP-glucose 4-epimerase (EC 5.1.3.2), also known as UDP-galactose 4-epimerase or GALE, is a homodimeric epimerase found in bacterial, plant, and mammalian cells. This enzyme performs the final step in the Leloir pathway of galactose metabolism, catalyzing the reversible conversion of UDP-galactose to UDP-glucose. GALE tightly binds nicotinamide adenine dinucleotide (NAD+), a co-factor required for catalytic activity.

Additionally, human and some bacterial GALE isoforms reversibly catalyze the formation of UDP-N-acetylgalactosamine (UDP-GalNAc) from UDP-N-acetylglucosamine (UDP-GlcNAc) in the presence of NAD+, an initial step in glycoprotein or glycolipid synthesis.