Involved in the biosynthesis of UDP-glucuronic acid (UDP-GlcA), providing nucleotide sugars for cell-wall polymers. H2O + 2 NAD(+) + UDP-alpha-D-glucose = 3 H(+) + 2 NADH + UDP-alpha-D-glucuronate Inhibited by UDP-xylose. Nucleotide-sugar biosynthesis; UDP-alpha-D-glucuronate biosynthesis; UDP-alpha-D-glucuronate from UDP-alpha-D-glucose: step 1/1. Restricted expression to the primary shoot in young seedlings. Later detected in hypocotyl, leaves and flowers. Specifically induced by H.schachtii (cyst nematodes) in nematode-induced syncytia. No visible phenotype. Belongs to the UDP-glucose/GDP-mannose dehydrogenase family. Was originally assigned as UGD4.