Sialyltransferases of developing rat brain.
The activity of four different sialyltransferases acting on N- or O-linked chains of glycoproteins was studied in brains of 19 days-old embryos, 1-day-old newborns and adult rats. By using asialofetuin, fetuin and N-acetyllactosamine as acceptors, it has been possible to measure independently the following enzyme activities: CMP-NeuAc:Gal beta 1-3GalNAc alpha(2-3)-sialyltransferase (EC 2.4.99.4), CMP-NeuAc:Gal beta 1-4GlcNAc alpha(2-3)-sialyltransferase (EC 2.4.99.6), CMP-NeuAc:Gal beta 1-4GlcNAc alpha(2-6)-sialyltransferase (EC 2.4.99.1) and CMP-NeuAc:NeuAc alpha 2-3Gal beta 1-3GalNAc alpha(2-6)-sialyltransferase (EC 2.4.99.7). The specific activity of the first three enzymes which act on asialylated acceptors showed a 2.6-fold decrease in a parallel manner after ontogenic development, while the activity of NeuAc alpha 2-3Gal beta 1-3GalNAc alpha(2-6)-sialyltransferase was four times lower in adult than in embryonic brain, showing a stronger dependence on ontogenic development. Despite the higher level of sialyltransferases able to act on glycoproteins, in fetal brain these glycoproteins do not contain a higher amount of sialic acid.
Dall'Olio
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Dipartimento di Patologia Sperimentale, Università di Bologna, Italy.
D000818:Animals; D000831:Animals, Newborn; D001212:Asialoglycoproteins / Q000378:metabolism; D001921:Brain / Q000196:embryology / Q000201:enzymology* / Q000254:growth & development; D002240:Carbohydrate Sequence; D002241:Carbohydrates / Q000032:analysis; D002851:Chromatography, High Pressure Liquid; D060748:Fetuins; D008969:Molecular Sequence Data; D019158:N-Acetylneuraminic Acid; D051381:Rats; D012794:Sialic Acids / Q000378:metabolism; D012799:Sialyltransferases / Q000378:metabolism*; D000509:alpha-Fetoproteins / Q000378:metabolism
D001212:Asialoglycoproteins; D002241:Carbohydrates; D060748:Fetuins; D012794:Sialic Acids; D000509:alpha-Fetoproteins; C017029:asialofetuin; D012799:Sialyltransferases; D019158:N-Acetylneuraminic Acid