UDP-α-D-galactose is an endogenous nucleotide sugar that is used by glycosyltransferases to transfer α-D-galactose residues to substrates.1 It is an agonist of the purinergic P2Y14 receptor (EC50 = 0.67 µM), an atypical P2Y receptor involved in the activation of dendritic and glial cells.2 Levels of UDP-α-D-galactose in red blood cells are decreased in patients with phenylketonuria (PKU) and maple syrup urine disease, inborn errors of amino acid metabolism characterized by mutations in the gene encoding phenylalanine hydroxylase (PAH) and a deficiency in the branched-chain α-keto acid dehydrogenase enzyme complex, respectively.3
1.Hennet, T.The galactosyltransferase familyCell Mol. Life Sci.59(7)1081-1095(2002) 2.Jacobson, K.A., Ivanov, A.A., de Castro, S., et al.Development of selective agonists and antagonists of P2Y receptorsPurinergic Signal.5(1)75-89(2009) 3.Gibson, J.B., Berry, G.T., Palmieri, M.J., et al.Sugar nucleotide concentrations in red blood cells of patients on protein- and lactose-limited diets: Effect of galactose supplementationAm. J. Clin. Nutr.63(5)704-708(1996)