CMP-N-acetylneuraminic Acid Hydroxylase
CMP-N-acetylneuraminic acid (CMP-NeuAc) hydroxylase catalyzes the hydroxylation of CMP-NeuAc to CMP-N-glycolylneuraminic acid (CMP-NeuGc) in the presence of hydrogen donor (NADH), cytochrome b5, and NADH-cytochrome b5 reductase (Kozutsumi et al. 1990; Kawano et al. 1994). This biosynthetic step is the rate limiting reaction for the expression of NeuGc, and only one gene encodes the hydroxylase in humans, chimpanzee, and mouse. In human genome, the deletion of 92 bp fragment which corresponds to exon 6 of mouse hydroxylase gene takes place. Humans are defective in the production of hydroxylase activity (Irie et al. 1998; Chou et al. 1998) and, therefore, lack the expression of NeuGc in normal tissues as a major component seen in other mammals.
KeywordsSialic Acid Germinal Center Incubation Mixture Hydroxylase Activity Enzyme Source
Unable to display preview. Download preview PDF.
- Naito Y, Takematsu H, Koyama S, Miyake S, Yamamoto H, Fujinawa R, Sugai M, Okuno Y, Tsujimoto G, Yamaji T, Hashimoto Y, Itohara S, Kawasaki T, Suzuki A Kozutsumi Y (2007) Germinal center marker GL7 probes activation-dependent repression of N-glycolylneuraminic acid, a sialic acid species involved in the negative modulation of B-cell activation. Mol Cell Biol 27:3008–3022PubMedCrossRefGoogle Scholar