title: Localization of methyltransferase activities throughout the endomembrane system of flax (Linum usitatissimum L) hypocotyls.
abstract: A microsomal fraction from flax hypocotyls (Linum usitatissimum L) showed a methylation ability from S-adenosyl-methionine on to the cell wall polysaccharides. Two kinds of methylation were found: (i) a methyl esterification of uronic acids in the oxalate extracts and (ii) an O-methylation of the hydroxyl groups in the NaOH extracts. The methyltransferase study showed a rapid decrease of the methyl esterification abilities, whereas the O-methylation on to the hydroxyl groups was maintained throughout the culture duration. The localization of such activities in the flax endomembrane system was performed using isopycnic centrifugation. Enzymic marker tests allowed us to identify the different membrane types. Methyltransferase activities in the different enriched fractions appeared to be associated with the Golgi apparatus for the O-methylation, and with the plasma membrane, Golgi apparatus and endoplasmic reticulum compartments for the carboxymethyl esterification.
authors.affiliation: Université de Rouen, SCUEOR-URA 203, Mont Saint Aignan, France.
authors.forename: M P
authors.initials: MP
authors.lastname: Vannier
authors.forename: B
authors.initials: B
authors.lastname: Thoiron
authors.forename: C
authors.initials: C
authors.lastname: Morvan
authors.forename: M
authors.initials: M
authors.lastname: Demarty
mesh_terms: D017766:Acid Anhydride Hydrolases; D000251:Adenosine Triphosphatases / Q000378:metabolism; D002458:Cell Fractionation; D002850:Chromatography, Gel; D004721:Endoplasmic Reticulum / Q000201:enzymology; D005964:Glucosyltransferases / Q000378:metabolism; D006056:Golgi Apparatus / Q000201:enzymology; D007425:Intracellular Membranes / Q000201:enzymology; D008565:Membrane Proteins; D008745:Methylation; D008780:Methyltransferases / Q000378:metabolism*; D008861:Microsomes / Q000201:enzymology; D009245:NADH Dehydrogenase / Q000378:metabolism; D010744:Phosphoric Monoester Hydrolases / Q000378:metabolism; D059828:Plant Cells; D010944:Plants / Q000201:enzymology*; D012436:S-Adenosylmethionine / Q000378:metabolism; D029702:Schizosaccharomyces pombe Proteins; D014461:Ultracentrifugation
chemical_list: D008565:Membrane Proteins; D029702:Schizosaccharomyces pombe Proteins; D012436:S-Adenosylmethionine; D009245:NADH Dehydrogenase; D008780:Methyltransferases; D005964:Glucosyltransferases; C020570:1,3-beta-glucan synthase; D010744:Phosphoric Monoester Hydrolases; D017766:Acid Anhydride Hydrolases; D000251:Adenosine Triphosphatases; C021446:inosine diphosphatase