2 Equipe de Glycobiologie et Biotechnologie (EA 3176), Institut des Sciences de la Vie et de la Santé, Université de Limoges, Faculté des Sciences, 123, Avenue Albert Thomas, 87060 Limoges, France; 3 Laboratoire de Physiologie et de Biochimie Végétales URA CNRS 571, Université de Poitiers, 25 rue du Faubourg St Cyprien, 86000, Poitiers, France; and 4 Laboratoire des transports intracellulaires, CNRS UMR 6037, IFRMP 23 Université de Rouen, UFR des Sciences, 76821 Mont St Aignan, Cedex, France
Received on October 30, 2001; accepted on February 13, 2002.
![]() |
Abstract |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Key words: 3/4 fucosyltransferase/Arabidopsis thaliana/Lewis a/Silene alba
![]() |
Introduction |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
All known animal 3/4-fucosyltransferases are type II membrane proteins composed of cytoplasmic, transmembrane, hypervariable, and catalytic domains. The catalytic domain contains two highly conserved peptide sequences named motifs I and II, which seem to be involved in GDP-Fuc recognition (Breton et al., 1998
; Oriol et al., 1999
). Leiter et al. (1999)
reported that the core
3-fucosyltransferase of Vigna radiata and the mammalian
3/4-fucosyltransferases have four common regions. Among them, two regions correspond to the characterized motifs I and II. The third sequence is named region A (153-LPQPSGTASILRSMESA) and is located 13 amino acids before motif I. The last common sequence is named region C (226-ISNCGARNFRLQALEALEKSNIKIDSYGG) and is located between motifs I and II.
Fucosylation in (1,4) linkage is well demonstrated in primates as confirmed by the presence of Lea and by the characterization of human and chimpanzee genes encoding
4-fucosyltransferases (Oriol et al., 1999
). However, in the plant kingdom, the detection of Lea epitopes was indirect proof of
4-fucosyltransferases activity in plant tissues (Fitchette-Laine et al., 1997
; Wilson et al., 2001b
). The present article provides demonstration of the occurrence of
4-fucosylation in Arabidopsis thaliana through Lea immunodetection and
-4FucT activity measurement. Cloning and expression of AtFT4 in COS-7 cells show that the gene encodes an enzyme able to transfer fucose in
1,4 linkage to type 1 acceptor substrates. While this work was under revision, Bakker et al. (2001)
described a gene of Beta vulgaris coding
4-FucT.
![]() |
Results |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
|
|
|
cDNA cloning
TBlastN search in DDBJ A. thaliana genome database (available online at http://arabidopsis.org) of fucosyltransferase motif II HYKFSLAFENSNE-EDYVTEKFF-QSLVAGTVPVV revealed three putative genes corresponding to the sequences FucTA (accession no. AP000419), FucTB (accession no. AC011807) and FucTC (accession no. AC021665). As described by Wilson et al. (2001a), FucTA and FucTB encode core
1,3 fucosyltranferases. However, no information was available on the putative function of FucTC. The complete sequence of FucTC has five putative start codons. We have chosen to amplify an open reading frame (ORF) of 1179 bp, named AtFT4, including the third ATG of FucTC as a start codon, because it is the only one conventionally positioned (Kozak, 1981
). The protein encoded by AtFT4 has a hydrophobic amino terminal domain of 16 residues (M1P16) probably playing the role of a transmembrane domain but without a cytosolic tail (Figure 3). Oligonucleotides (S1; S2; and the nested ones, S3, S4) including start and stop codons were designed and used as primers for polymerase chain reaction (PCR) amplification of the AtFT4 cDNA from 10-day-old A. thaliana leaves. One fragment of approximately 1200 bp was obtained. After DNA sequencing, it was found to be strictly identical to the predicted ORF of the genomic DNA. PCR amplification of the same sequence on genomic DNA gave a longer fragment (1728 bp) than the cDNA (1179 bp), suggesting the presence of intronic sequences in the gene. Three exons (E1, E2, E3) and two introns (I1, I2) spanning 465 bp and 84 bp, respectively, were identified (Figure 4).
|
|
Southern blot and northern blot analyses
A mono-exonic probe (1179 bp) was used in hybridization studies with genomic DNA of two ecotypes of A. thaliana (cv landsberg and cv columbia) digested with EcoRI. A single band of about 3 kb was detected for each A. thaliana digested DNA suggesting the presence of only one 4-fucosyltransferase gene in the A. thaliana genome (Figure 5A). Another digest of genomic DNA with EcoRI/BamHI and an exhaustive search in DDBJ database confirmed that A. thaliana genome contains a single copy of AtFT4 (data not shown).
|
Expression of AtFT4 in mammalian COS-7 cells
The AtFT4 cDNA was subcloned into the mammalian expression vector pTARGET and transiently transfected into COS-7 cells to determine the activity of the enzyme encoded by AtFT4 in vitro. The fucosyltransferase activities were measured in the cellular homogenates and in the culture medium of COS-7 cells using Galß1,4GlcNAc-Biotin (type 2), Galß1,3GlcNAc-Biotin (type 1), and Fuc1,2Galß1,3GlcNAc-Biotin (H-type 1) as acceptor substrates.
No fucosyltransferase activity was detected in the protein extract of COS-7 cells transfected with pTARGET/AtFT4 whatever the acceptor substrate. Nevertheless, culture medium proteins were able to transfer Fuc on type 1 (0.2 pmol min1 mg1 protein) and on H-type 1 (0.2 pmol min1 mg1 protein) but not on type 2 acceptors. Our results demonstrate that the A. thaliana protein encoded by AtFT4 cDNA is an enzyme secreted into the culture medium of transfected COS-7 cells and is able to transfer Fuc in (1,4)-linkage. Kinetic studies (Table II) showed that Fuc transfer from GDP-Fuc to Type 1 acceptor progressively increased with the incubation time. Varying the protein concentration within the reaction mixture proportionally changed the fucosyltransferase activity. These results confirm the enzymatic properties of the protein encoded by AtFT4.
|
![]() |
Discussion |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Finer analysis of the peptide sequence of AtFT4 showed that motif II defined in mammalian lactosamine-(3/4)-fucosyltransferases is conserved between animal and plant (55% identity) (Figure 6). This motif seems to be involved in GDP-Fuc binding. We recently characterized the acceptor motif of vertebrate fucosyltransferases (Dupuy et al., 1999
). One amino acid (W) is involved in enzyme specificity (-HHWD- for lactosamine-
1,4-fucosyltransferase, and HHRD- for lactosamine-
1,3-fucosyltransferase). AtFT4 contains a sequence 57-VLVAYKKWD-67, which may correspond to the acceptor-binding motif (Figure 3). This motif is also found in the B. vulgaris
4-FucT protein (56-LLGAFRKWD-64), but is absent in FucTA, FucTB, and V. radiata FucT c3, which are core -
(1,3)-fucosyltransferases. However, two conserved cysteins (C-377 and C-380) corresponding to the residues involved in disulfide bonds of the lactosamine-fucosyltransferases (Holmes et al., 2000
) were also found in AtFT4.
|
![]() |
Materials and methods |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Molecular standard methods
Plant nucleic acids of shoots of 10-day-old plants were prepared with the respective DNeasy and RNeasy kits from Qiagen GmbH (Hilden, Germany). Genomic and cDNA sequences of AtFT4 were amplified by nested PCR with two sets of primers: S1, 5'-AGGAATCAATCACACCATGCC-3' and S2, 5'-GCAATGGCCGCTCTACTAATG-3'; and S3, 5'-GCAATGGCCGCTCTACTAATG-3' and S4, 5'-CATCAAACTCCGGCGTTCTTCCC-3'). Before sequencing, PCR products were cloned into the pGEM-T Easy vector (Promega, Madison, WI). Transfections of COS-7 cells were carried out using the pTARGET expression vector (Promega).
Southern blot and northern blot analysis
Arabidopsis genomic DNA was digested with EcoRI or EcoRI/BamHI and fractionated by electrophoresis through 0.8% (w/v) agarose gel. After depurination (15 min) with 0.25 N HCl and denaturation (30 min) with 0.4 N NaOH, DNA was transferred on Hybond-N+ membranes (Amersham, Arlington Heights, IL).
RNA from Arabidopsis tissues was isolated using the Qiagen Plant Mini Kit (Qiagen). For northern blot analysis, RNA was size-fractionated on formaldehyde agarose gels and transferred to Hybond-N+ membranes (Amersham).
Hybridization was carried out with a 1179-bp monoexonic probe generated by PCR amplification on cDNA. Twenty-five nanograms of probe were labeled with PCR DIG Probe Synthesis Kit (Boehringer-Mannheim, Germany). Hybridization was carried out overnight at 42°C in DIG Easy Hyb (Boehringer-Mannheim). Blots were washed three times for 15 min each at 65°C with 2x SSC/0.1% sodium dodecyl sulfate (SDS), 1x SSC/0.1% SDS, and 0.2x SSC/ 0.1% SDS, then analyzed after exposure to X-ray films (Kodak, Kyoto, Japan) for 1 h at 80°C.
DNA sequencing
Sequencing was performed using T7 promoter and pUCM13 reverse primers for DNA cloned into pGEM-T Easy vector or directly with primers used for PCR amplification. A dye labeling chemistry (kit PRISM Ready Reaction Ampli Taq FS) and the ABIPrism 310 Genetic Analyzer (Perkin Elmer, Norwalk, CT) were used.
Transient expression of Arabidopsis cDNA
The full-length AtFT4 cDNA (1,240 bp) was inserted into the pTARGET (pTARGET/AtFT4) to transiently transfect COS-7 cells. SuperFect transfection reagent (Qiagen) was used according to the protocol described by the manufacturer. After 48 h, COS-7 cells were harvested and washed with phosphate buffered saline (PBS), and proteins were subsequently extracted in lysis buffer (1% [v/v] Triton X100, 10 mM sodium cacodylate [pH 6], 20% [v/v] glycerol, 1 mM dithiothreitol) for 2 h at 48°C. The suspension was then centrifuged at 12,000 x g for 10 min at 4°C, and the supernatant was used for assays. Media of transfected and not transfected COS-7 cells were concentrated before use for enzymatic assays.
3/4-Fucosyltransferase assay
Fucosyltransferase assays were conducted in 60 ml containing 25 mM sodium cacodylate (pH 6.5), 5 mM ATP, 20 mM MnCl2, 10 mM -L-fucose, 3 µM GDP-[14C]-fucose (310 mCi/mmol; Amersham), and 50 µg of proteins (from crude extract or supernatant of transfected COS-7 cells). The mixture was incubated 1 h or 3 h at 37°C. Acceptor substrates (type 1, type 2, and H-type 1 from Syntesome, Munich) were used at the concentration of 0.1 mM. The reaction was stopped by addition of 3 ml cold water. The reaction mixture was then applied to a conditioned Sep-Pak C18 reverse chromatography cartridge (Waters Millipore, Bedford, MA). Unreacted GDP-[14C]-fucose was washed off with 15 ml of water. The radiolabeled reaction product was eluted with 2x 5 ml ethanol, collected directly into scintillation vials, and counted with two volumes of biodegradable counting scintillant (Amersham) in a liquid scintillation beta counter (Liquid scintillation analyzer, Tri-Carb-2100TR, Packard).
Immunocytochemical procedure
The antibodies used were raised against the plant Lea glycoepitope (Fitchette-Laine et al., 1997).
A. thaliana cells were fixed for 1530 min in a mixture of 1.5% (w/v) paraformaldehyde and 0.5% glutaraldehyde in 50 mM phosphate buffer, pH 7.2 (Fleurat-Lessard et al., 1995). Abundant washing in the same buffer was followed by 4 min postfixation in 1% (v/v) OSO4, dehydratation in ethanol series, and overnight embedding in London Resin White. Polymerization occurred in gelatin capsules at 60°C for 24 h.
The immunogold reaction on thin sections, carefully spread with toluene vapor on parlodion-coated gold grids, was performed at 20°C, as previously described (Bouché-Pillon et al., 1994a,b). The procedure accommodated a compromise between the preservation of structure and antigenicity. Solution was filtered (0.1 µm pores, Millipore MFVCWP). The sections, hydrated in deionized water, were then in the dark etched by 0.56 M NaIO4 and 0.1 N HCl, and washed for 15 min with PBS, 0.1%(v/v) Triton X-100, and 0.2% (v/v) Gly at pH 7.2. Nonspecific sites were saturated for 45 min by goat serum in PBS, 0.2% (v/v) Triton X-100, 0.2% (v/v) Tween 20, and 0.1% (w/v) bovine serum albumin (BSA); sections were incubated overnight with the Lea antibody at a 1:50 dilution. After washing in PBS, sections were placed for 40 min on Tris-buffered saline (pH 8.2) 0.2% (v/v) Tween, 0.2% (v/v) Triton X-100, 1% (w/v) BSA, and goat serum before the 3-h application of a 15-nm gold particle labeled goat anti-mouse IgG at a 1:40 dilution. The sections, washed in Tris-buffered saline and deionized water, were contrasted in uranyl acetate at saturation in water and in lead citrate. Controls were as for the semithin sections. Specimens were observed with an electron microscope (100C, JEOL) operated at 80 KV.
Protein extraction and western blot experiments
Cells were harvested by filtration on Whatman 41 paper with a Büchner funnel and disrupted with liquid nitrogen.
The protein fraction was extracted into cacodylate buffer (200 mM sodium cacodylate, pH 7.0, containing 1% (w/v) Triton X-100; Sigma). The homogenate was centrifuged at 14,000 x g for 30 min. The supernatant constitutes the crude protein extract. For microsome preparation, disrupted cells were homogenized on ice in 200 mM HEPES-KOH buffer (pH 7) containing 1 mM dithiothreitol and 0.4 M sucrose (Misawa et al., 1996). The homogenate was filtered through cloth nylon and centrifuged at 5000 x g for 10 min at 4°C. The supernatant was then centrifuged again at 100,000 x g for 1 h at 4°C (Beckman L8-80). The pellet was then resuspended in cacodylate buffer.
Protein extracts were obtained by homogenizing plant material in a solution containing 0.7 M sucrose, 0.5 M Tris, 30 mM HCl, and 2% (v/v) ß-mercaptoethanol. After incubation on ice for 30 min, the homogenate was centrifuged for 5 min at 5000 x g. The supernatant was mixed vigorously with one volume of saturated phenol, left on ice for at least 30 min, and centrifuged at 10,000 x g for 30 min. The upper phenolic phase was precipitated overnight at 4°C by the addition of five volumes of methanol containing 0.1 M ammonium acetate. The preparation was then centrifuged for 30 min at 10,000 x g. The pellet was washed once with 0.1 M ammonium acetate in methanol and twice with acetone before being resuspended in sample buffer (62.5 mM TrisHCl, pH 6.8, containing 10 mM dithiothreitol, 10% [v/v] glycerol).
Protein amount was determined by the Bradford method using BSA as a standard (Bradford, 1976).
The crude extracts were analysed by SDSpolyacrylamide gel electrophoresis (PAGE) using a 12% acrylamide Tris-glycine gel (Laemmli, 1970). Proteins were visualized by Coomassie blue staining and transferred onto nitrocellulose membrane (Schleicher & Schuell, Germany). Membrane coating was performed overnight at 4°C with Tris-buffered saline containing 0.1% (v/v) Tween 20 and 5% (w/v) BSA (TBS-T-BSA). After three washings in TBS-T, the membrane was incubated for 1 h at 20°C with a mouse anti-Lea antibody in TBS-T-BSA buffer at 1:1000 dilutions. Rabbit anti-mouse Ig coupled to horseradish peroxidase (Amersham, England), was used at 1:1000 dilution. The western blots were developed according to the ECL detection kit (Amersham).
![]() |
Abbreviations |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
![]() |
Footnotes |
---|
![]() |
References |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Bakker, H., Schijlen, E., De Vries, T., Schiphorst, W.E.C.M., Jordi, W., Lommen, A., Bosch, D., and Van Die, I. (2001) Plant membres of 1, 3/4-fucosyltransférase, potentially involved in Lewis a biosyntheses, and two core
1, 3-fucosyltransferases FEBS Lett., 507, 307312.[CrossRef][ISI][Medline]
Bouché-Pillon, S., Fleurat-Lessard, P., Fromont, J.C., Serrano, R., and Bonnemain, J.L. (1994a) Immunolocalisation of the plasma membrane H+-ATPase in minor veins of Vicia faba in relation to phloem loading. Plant Physiol., 105, 691697.
Bouché-Pillon, S., Fleurat-Lessard, P., Serrano, R., and Bonnemain, J.L. (1994b) Asymmeatric distribution of the plasma membrane H+-ATPase in embryo of Vicia faba L. with special reference to transfer cells. Planta, 193, 392397.[ISI]
Bradford, M.M. (1976) A rapid and sensitive method for the quantification of microgram quantities utilizing the principle of protein-dye binding. Anal. Biochem., 72, 248254.[CrossRef][ISI][Medline]
Breton, C., Oriol, R., and Imberty, A. (1998) Conserved structural features in eukaryotic and prokaryotic fucosyltransferases. Glycobiology, 8, 8794.
Costache, M., Cailleau, A., Fernandez-Mateos, P, Oriol, R., and Mollicone, R. (1997) Advances in molecular genetics of alpha-2- and alpha-3/4- fucosyltransferases. Transfus. Clin. Biol., 4, 367382.[ISI][Medline]
Dupuy, F., Petit, J.M., Mollicone, R., Oriol, R., Julien, R., and Maftah, A. (1999) A single amino acid in the hypervariable stem domain of vertebrate alpha1, 3/1, 4-fucosyltransferases determines the type 1/type 2 transfer. Characterization of acceptor substrate specificity of the lactosamin enzyme by site-directed mutagenesis. J. Biol. Chem., 274, 1225712262.
Fitchette, A.C., Cabanes-Macheteau, M., Marvin, L., Martin, B., Satiat-Jeunemaitre, B., Gomord, V., Crooks, K., Lerouge, P., Faye, L., and Hawes, C. (1999) Biosynthesis and immunolocalization of Lewis a-containing N-glycans in the plant cell. Plant Physiol., 121, 333344.
Fitchette-Laine, A.C., Gomord, V., Cabanes, M., Michalski, J.C., Saint Macary, M., Foucher, B., Cavelier, B., Hawes, C., Lerouge, P., and Faye, L. (1997) N-glycans harboring the Lewis a epitope are expressed at the surface of plant cells. Plant J., 12, 14111417.[CrossRef][ISI][Medline]
Fleurat-Lessard, P., Bouché-Pillon, S., Leloup, C., Lucas, W.J., Serrano, R., and Bonnemain, J.L. (1995) Absence of plasma membrane H+-ATPase in plasmodesmata located in pit-fields of young reactive pulvinus of Mimosa pudica L. Ann. Bot., 50, 8392.
Holmes, E.H., Yen, T.Y, Thomas, S., Joshi, R., Nguyen, A., Long, T., Gallet, F., Maftah, A., Julien, R., and Macher, B. (2000) Human 1, 3/4 fucosyltransferases. Characterization of highly conserved cysteine residues and N-linked glycosylation. J. Biol. Chem., 275, 2423724245.
Kimura, Y., Hase, S., Kobayashi, Y., Kyogoku, Y., Funatsu, G., and Ikenaka, T. (1987) Possible pathway for the processing of sugar chains containing xylose in plant glycoproteins deduced on structural analyses of sugar chains from Ricinus communis lectins. J. Biochem., 101, 10511054.[Abstract]
Kozak, M. (1981) Possible role of flanking nucleotides in recognition of AUG initiator codon by eucaryotic ribosomes. Nucleic Acids Res., 24, 52335262.
Laemmli, U.K. (1970) Cleavage of structural proteins during the assembly of the head of bacteriophage T4. Nature, 227, 680685.[ISI][Medline]
Leiter, H., Mucha, J., Staudacher, E., Grimm, R., Glossl, J., and Altmann, F. (1999) Purification, cDNA cloning, and expression of GDP-L-Fuc:Asn-linked GlcNAc alpha1, 3-fucosyltransferase from mung beans. J. Biol. Chem., 274, 2183021839.
Lerouge, P., Cabanes-Macheteau, M., Rayon, C., Fitchette-Laine, A.C., Gomord, V., and Faye, L. (1998) N-glycoprotein biosynthesis in plants: recent developments and future trends. Plant Mol. Biol., 38, 3148.[CrossRef][ISI][Medline]
Lhernould, S., Costa, G., Petit, J.M., Julien, R., and Morvan, H. (1997) Alpha (1, 4) fucosyltransferase activity: a comparative study between Silene alba and Arabidopsis thaliana cell suspension cultures. Glycoconj. J., 14, S126.
Lowe, J.B., Stoolman, L.M., Nair, R.P., Larsen, R.D., Behrend, T.L., and Marks, R.M. (1990) ELAM-1 dependent cell adhesion to vascular endothelium determined by a transfected human fucosyltransferase cDNA. Cell, 63, 475484.[ISI][Medline]
Melo, N.S., Nimtz, M., Conradt, H.S., Fevereiro, P.S., and Costa, J. (1997) Identification of the human Lewis a carbohydrate motif in a secretory peroxidase from a plant cell suspension culture (Vaccinium myrtillus L.). FEBS Lett., 415, 186191.[CrossRef][ISI][Medline]
Misawa, H., Tsumauraya, Y., Kaneko, Y., and Hashimoto, Y. (1996) -L-Fucosyltransferases from radish primary roots. Plant Physiol., 110, 665673.
Oriol, R., Mollicone, R., Cailleau, A., Balanzino, L., and Breton, C. (1999) Divergent evolution of fucosyltransferase genes from vertebrates, invertebrates, and bacteria. Glycobiology, 9, 323334.
Rayon, C., Cabanes-Macheteau, M., Loutelier-Bourhis, C., Salliot-Maire, I., Lemoine, J., Reiter, W.D., Lerouge, P., and Faye, L. (1999) Characterization of N-glycans from Arabidopsis. Application to a fucose- deficient mutant. Plant Physiol., 119, 725734.
Roberts, LM. and Lord, JM. (1981) The synthesis of Ricinus communis agglutinin, cotranslational and posttranslational modification of agglutinin polypeptides. Eur. J. Biochem., 119, 3141.[Abstract]
Staudacher, E. and Marz, L. (1998) Strict order of (Fuc to Asn-linked GlcNAc) fucosyltransferases forming core-difucosylated structures. Glycoconj. J., 15, 355360.[CrossRef][ISI][Medline]
Staudacher, E., Altmann, F., Glossl, J., Marz, L., Schachter, H., Kamerling, J.P., Hard, K., and Vliegenthart, J.F. (1991) GDP-fucose: beta-N-acetylglucosamine (Fuc to (Fuc alpha 1, 6GlcNAc)-Asn-peptide)alpha 1, 3-fucosyltransferase activity in honeybee (Apis mellifica) venom glands. The difucosylation of asparagine-bound N-acetylglucosamine. Eur. J. Biochem., 199, 745751.[Abstract]
Staudacher, E., Altmann, F., Marz, L., Hard, K., Kamerling, JP. and Vliegenthart, JF. (1992) Alpha 1-6(alpha 1-3)-difucosylation of the asparagine-bound N- acetylglucosamine in honeybee venom phospholipase A2. Glycoconj. J., 9, 8285.[ISI][Medline]
Staudacher, E., Dalik, T., Wawra, P., Altmann, F., and Marz, L. (1995) Functional purification and characterization of a GDP-fucose: beta-N- acetylglucosamine (Fuc to Asn linked GlcNAc) alpha 1, 3- fucosyltransferase from mung beans. Glycoconj. J., 12, 780786.[ISI][Medline]
Staudacher, E., Altmann, F., Wilson, I.B., and Marz, L. (1999) Fucose in N-glycans: from plant to man. Biochim. Biophys. Acta, 1473, 216236.[ISI][Medline]
Van Die, I., Gomord, V., Kooyman, F.N., van den Berg, T.K., Cummings, R.D., and Vervelde, L. (1999) Core alpha13-fucose is a common modification of N-glycans in parasitic helminths and constitutes an important epitope for IgE from Haemonchus contortus infected sheep. FEBS Lett., 463, 189193.[CrossRef][ISI][Medline]
Wilson, I.B.H., Rendic, D., Freilinger, A., Dumic, J., Altmann, F., Mucha, J., Müller, S., and Hauser, M.T. (2001a) Cloning and expression of cDNA encoding 1, 3-fucosyltransferase homologues from Arabidopsis thaliana. Biochim. Biophys. Acta, 1527, 8896.[ISI][Medline]
Wilson, I.B.H., Zeleny, R., Kolarich, D., Staudacher, E., Stroop, C.J.M., Kamerling, J.P., and Altmann, F. (2001b) Analysis of Asn-linked glycans from vegetable foodstuffs: widespread occurrence of Lewis a, core 1, 3-linked fucose and xylose substitutions. Glycobiology, 11, 261274.
Zeleny, R., Altmann, F., and Praznik, W. (1999) Structural characterization of the N-linked oligosaccharides from tomato fruit. Phytochem., 51, 199210.[CrossRef][ISI]