title: Glycosyltransferases in the Golgi membranes of onion stem.
abstract: Cell fractions consisting largely of Golgi membranes were prepared from the meristematic region of the onion. Several enzyme activities were found to be localized in these fractions: inosine diphosphatase, galactosyltransferases and glucosyltransferases. The fractions catalysed the transfer of [(14)C]galactose from UDP-galactose to endogenous and cell-sap acceptors, to N-acetylglucosamine and to ovalbumin. In the presence of bovine alpha-lactalbumin, transfer to glucose (lactose synthesis) was catalysed. [(14)C]Glucose was transferred from UDP-glucose to endogenous and cell-sap acceptors, to cellobiose and to fructose (sucrose synthesis). All these activities were latent, being potentiated by detergents (Triton X-100 or sodium deoxycholate). The characteristics of some of these enzyme activities are described and their biological significance is discussed.
mesh_terms: D002250:Carbon Radioisotopes; D002499:Centrifugation, Density Gradient; D003902:Detergents / Q000378:metabolism; D005690:Galactose; D005944:Glucosamine / Q000378:metabolism; D005964:Glucosyltransferases / Q000302:isolation & purification / Q000378:metabolism*; D006056:Golgi Apparatus / Q000201:enzymology*; D006602:Hexosyltransferases; D007288:Inosine; D007700:Kinetics; D008566:Membranes / Q000201:enzymology; D008854:Microscopy, Electron; D010047:Ovalbumin / Q000378:metabolism; D010744:Phosphoric Monoester Hydrolases / Q000302:isolation & purification; D010944:Plants / Q000201:enzymology*; D013347:Subcellular Fractions; D014500:Uracil Nucleotides / Q000378:metabolism
chemical_list: D002250:Carbon Radioisotopes; D003902:Detergents; D014500:Uracil Nucleotides; D007288:Inosine; D010047:Ovalbumin; D005964:Glucosyltransferases; D006602:Hexosyltransferases; D010744:Phosphoric Monoester Hydrolases; D005944:Glucosamine; D005690:Galactose