Skip Navigation


Glycobiology Advance Access originally published online on July 25, 2007
Glycobiology 2007 17(10):1077-1083; doi:10.1093/glycob/cwm077
This Article
Right arrow Abstract Freely available
Right arrow FREE Full Text (PDF) Freely available
Right arrow All Versions of this Article:
17/10/1077    most recent
cwm077v1
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in ISI Web of Science
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Add to My Personal Archive
Right arrow Download to citation manager
Right arrow Search for citing articles in:
ISI Web of Science (2)
Right arrowRequest Permissions
Right arrow Disclaimer
Google Scholar
Right arrow Articles by Lescar, J.
Right arrow Articles by Imberty, A.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Lescar, J.
Right arrow Articles by Imberty, A.
Social Bookmarking
Add to CiteULike   Add to Connotea   Add to Del.icio.us  
What's this?

© The Author 2007. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oxfordjournals.org

Structural basis for recognition of breast and colon cancer epitopes Tn antigen and Forssman disaccharide by Helix pomatia lectin

Julien Lescar2,3,4, Jean-Frederic Sanchez2,4, Aymeric Audfray4, Jean-Luc Coll5, Christelle Breton4, Edward P Mitchell1,6 and Anne Imberty1,4

4 Centre de Recherches sur les Macromolécules Végétales, CNRS (affiliated with Université Joseph Fourier), BP53, 38041 Grenoble Cedex 09, France
5 INSERM, U823, Cibles Diagnostiques ou Thérapeutiques et Vectorisation des Drogues dans le Cancer du Poumon Institut Albert Bonniot, 38706 La Tronche, France
6 ESRF, Experiments Division, BP 220, F-38043, Grenoble Cedex, France

1 To whom correspondence should be addressed; email: Mitchell{at}esrf.fr or imberty{at}cermav.cnrs.fr

Received on April 10, 2007; revised on June 6, 2007; accepted on July 10, 2007


   Abstract
Top
 Abstract
Introduction
 Results and discussion
 Conclusions
 Funding
 References
 
Helix pomatia agglutinin (HPA) is a lectin that has been used extensively in histopathology, since its binding to tissue sections from breast and colon cancers is correlated with the worst prognosis for the patients. The lectin recognizes {alpha}-D-N-acetylgalactosamine ({alpha}GalNAc) containing epitopes which are only present in cancer cell lines having a high likelihood to undergo metastasis, such as the HT29 cancer colon cell line. Several breast cancer cell lines have also been shown to be labeled, although IGROV1, an ovarian cancer cell line, is not. Inhibition studies, using GalNAc monosaccharides, are reported here, showing that the labeling is dependent upon the presence of carbohydrate epitopes. The crystal structures of the lectin complexed with two GalNAc containing epitopes associated with cancer, the Tn ({alpha}GalNAc-Ser) and Forssman ({alpha}GalNAc1-3GalNAc) antigens, show the lectin's specificity for GalNAc is due to a particular network of hydrogen bonds. A histidine residue makes hydrophobic contact with the aglycon, rationalizing the preference for GalNAc bearing an additional sugar or amino acid in the {alpha} position. These structures provide the molecular basis for the use of HPA in metastasis research.

Key words: breast cancer / colon cancer / Forssman antigen / Helix pomatia lectin / Tn antigen


   Introduction
Top
 Abstract
 Introduction
Results and discussion
 Conclusions
 Funding
 References
 
Glycoproteins and glycolipids present on the surface of cancer cells are markedly different from those of normal cells (Hakomori 1984Go; Feizi 1985Go). Some of these changes in cell surface properties have been directly correlated with tumor progression and metastatic potential (Dennis et al. 1999Go). The expression of N-acetylgalactosamine (GalNAc) on the surface of cancer cells is one of the signatures of the altered glycosylation pathway, and has been the subject of many investigations (Brooks 2000Go). Amongst GalNAc-containing cancer epitopes, the Tn determinant ({alpha}GalNAcO-Ser/Thr) is one of the most specific human tumor associated structures. Present in mucin-type O-glycans, this antigen is shielded in both healthy and benign-diseased tissues, but uncovered in approximately 90% of carcinomas (Springer 1997Go). The Forssman antigen ({alpha}GalNAc1-3{alpha}GalNAc-R) is another cancer epitope of interest. Present on glycolipids, it is a normal constituent of fetal tissues and virtually absent in healthy adults, but it has been detected in elevated levels in various human lung, breast, and gastric cancer cell lines (Hakomori 1984Go).

With their fine specificity for oligosaccharides, lectins isolated from some legume plants have proven to be useful markers in cancer histochemistry. For example, Vicia villosa and Dolichos biflorus beans have been used as sources of {alpha}GalNAc-binding lectins. Two decades ago, the binding of an agglutinin from the roman snail (Helix pomatia – HPA), was demonstrated to have a predictive value for breast cancer recurrence and survival (Leathem and Brooks 1987Go). These results initiated the strong interest in HPA as a potential marker for cancer research (Brooks and Wilkinson 2003Go). When applied to tissue sections from primary breast and colon cancers, HPA was shown to bind to tumors from patients with a very poor prognosis (Brooks 2000Go; Mitchell and Schumacher 1999Go). Moreover, when various human and colon cancer cell lines were transplanted into severe combined immuno deficient (SCID) mice, only the HPA positive cell lines metastasized, whereas the HPA-negative ones did not (Schumacher and Adam 1997Go). When compared to legume lectin binding to lung adenocarcinomas, only HPA was demonstrated to have a significant independent prognostic factor for survival (Laack et al. 2002Go). The {alpha}GalNAc-containing glycoconjugates that are associated with metastasis and which bind to HPA have not yet been identified. Both the Tn antigen present on mucins and the Forssman antigen present on glycolipids are good candidates. However, the results of recent studies are in favor of a more complex epitope, named HPAgly-1, that has been found associated with 11 glycoproteins overexpressed in breast cancer (Dwek et al. 2001Go).

Early biochemical studies on HPA demonstrated that the protein assembles as a hexamer with a total molecular weight of 79 kDa (Hammarström and Kabat 1969Go). The binding preference was established to be (strongest preference first): Forssman antigen ({alpha}GalNAc1-3GalNAc-R) > Blood group A substance ({alpha}GalNAc1-3[{alpha}Fuc1-2]Gal) > Tn antigen ({alpha}GalNAc-Ser/Thr) > GalNAc > GlcNAc; therefore confirming the specificity for a terminal {alpha}-N-acetyl-D-galactosamine ({alpha}GalNAc) residue (Wu and Sugii 1991Go). The recent determination of the crystal structure of HPA confirmed the hexameric state of the lectin, each monomer consisting of a six-stranded antiparallel ß-sandwich (Sanchez et al. 2006Go). This unique oligomeric arrangement results in groups of three GalNAc binding sites, with each group located at opposite ends of the hexamer. The GalNAc specificity is created by a network of hydrogen bonds that involves two neighboring monomers.

We report here the crystal structures of HPA complexed with two ligands that are described as tumor markers: the Tn ({alpha}GalNAc-Ser) and Forssman ({alpha}GalNAc1-3GalNAc) antigens. Although the oligosaccharide epitope is not yet characterized the HPA binding to HT29 cells, a highly metastatic colon cancer cell line, has been shown to be inhibited by GalNAc. The description of the complexes allows the fine specificity of the lectin for GalNAc-containing epitopes to be rationalized.


   Results and discussion
Top
 Abstract
 Introduction
 Results and discussion
Conclusions
 Funding
 References
 
Labeling of colon cancer cells with biotinylated HPA
The purity and binding properties of commercial HPA extracted from snails may present lot-to-lot variations. The absence of protein contaminant was previously verified by gel electrophoresis and mass spectrometry, but this previous study has shown the presence of glycoforms as well as eventual metal contaminants such as Zn2+ ions (Sanchez et al. 2006Go). Prior to structural study, we ensured that the commercial source of HPA used for crystallization trials binds to cancer cells in a GalNAc-dependent manner. The HT29 cells were chosen since they are classically considered as a positive control for HPA binding (Schumacher and Adam 1997Go).

The labeling and inhibition conditions were adapted from those described previously for fixed tissues (Brooks and Leathem 1998Go). Figure 1A and B displays the results obtained using a solution of biotinylated HPA at 20 µg/mL. More than 90% of the HT29 cells are labeled. This result is concentration dependent, since 70% of the cells are labeled for a HPA concentration of 10 µg/mL and only 40% for a concentration of 5 µg/mL (data not shown). Furthermore, the labeling is fully inhibited when GalNAc (100 µM) is added to the HPA solution (Figure 1C).


Figure 1
View larger version (38K):
[in this window]
[in a new window]
[Download PowerPoint slide]
  		Fig. 1 Biotin-HPA labeling of HT29 cancer colon cells, (A) Bar = 100 µm. (B) Closer view of labeled cells. (C) Negative control in the presence of 100 mM GalNAc. Cy5-HPA labeling of (D) HT29 colon cancer cell lines. (E) human non small cell lung cancer H1299. (F) negative labeling of IGROV1 ovarian cancer cell lines and (G) control experiment in presence of 100 mM GalNAc. (D to G: nuclei are blue stained with 5 µM Hoechst 33342).

 
The labeling of other cancer cell lines has also been performed with the use of Cy5-labeled HPA. As previously reported (Schumacher and Adam 1997Go), the strongest labeling is observed for the colon and breast cell lines that are reported to have the higher metastasis potential (Table I). Figure 1D shows the strong positive labeling of HT29 or weak homogenous labeling with the human non small cell lung carcinoma H1299 (Figure 1E), whereas the ovarian cancer cell line IGROV1 is not labeled (Figure 1F). The control experiment with GalNAc (100 µM) added to the HPA solution is shown in Figure 1G and no labeling is observed. Similarly, no color is observed when cells are incubated in Cy5 not attached to HPA. In several cases, such as the human non small cell lung cancer cell line A539 (data not shown), the cells are not labeled, except for a small percentage that display strong staining (1–10%). This behavior has been reported before (Brooks et al. 2001Go) and may correspond either to the "fugitive" expression of particular glycoconjugates on the surface of cultured cancer cell during their cycles, or to the apparition of metastatic character in a subpopulation of cells.


View this table:
[in this window]
[in a new window]

  		Table I Labeling of different cancer cell lines by cy5-HPA

 
Crystal structure of HPA/cancer epitope complexes
HPA co-crystallized with both ligands yielded crystals of space group P6322 and diffracting to 2.8 Å resolution (Table II). The structures were determined using the molecular replacement method with the crystal structure of HPA/GalNAc complex (PDB code 2CCV) as the search probe. The structure complexed with GalNAc residue, together with the peptide and nucleotide sequences, has been described previously (Sanchez et al. 2006Go).


View this table:
[in this window]
[in a new window]

  		Table II Data collection and refinement statistics

 
In both complexes, HPA adopts an immunoglobulin like fold formed by six ß-strands and one long loop protruding from the barrel (Figure 2). An N-linked glycan is found attached to Asn34 of each monomer, but the quality of the electron density permitted the modeling only of the first GlcNAc residue. The overall quaternary state is hexameric with the trimers associated back-to-back through disulfide bridges formed from the face-to-face Cys42 residues (Figure 2B). The resulting geometry consists of two negatively charged and almost flat faces that are almost 100 Å apart (Figure 2C). Each face carries three ligand binding sites, created between the monomers (Figure 2A), on the points of an equilateral triangle with sides of 25 Å and in an ideal topology for the multivalent binding of carbohydrate epitopes on cancer cell surfaces.


Figure 2
View larger version (54K):
[in this window]
[in a new window]
[Download PowerPoint slide]
  		Fig. 2 Structure of HPA complexed with Tn antigen. (A) Trimer with Tn antigen ligand displayed as ball-and-sticks. (B) Side view of the hexamer with Tn ligand and intramolecular disulfide bridges displayed as capped sticks and bound GlcNAc of N-glycan as lines. (C) Connolly surface of the hexamer of color coded according to the electrostatic potential (from blue for negatively charged regions to red for positively charged ones).

 
The Tn carbohydrate binding site consists of a shallow pocket, but involves a strong network of hydrogen bonds between the monosaccharide and the protein (Figure 3A and Table III). The lectin preference for the galacto configuration, i.e., axial orientation of the O4 oxygen, is determined by three hydrogen bonds formed between this hydroxyl group and the side chains of neighboring amino acids. The higher affinity for N-acetyl containing monosaccharides is due to a hydrogen bond between the carbonyl of this group and an amine nitrogen of the protein backbone. Other hydrogen bonds involve the hydroxyl groups O3 and O6, and the ring oxygen O5. Van der Waals contacts are limited to the CH2 group of C6 that interacts with Tyr89 of the neighboring monomer. The serine residue of the Tn antigen does not establish hydrogen bonds with the protein. However, a strong hydrophobic interaction is created between the C{alpha} of the Tn serine with the side chain of His84. The serine extends out from the binding site in the flat surface of the trimer, thereby sterically allowing a longer ligand, e.g., a {alpha}GalNAc-containing mucin, to be bound by the snail lectin (Figure 3B).


Figure 3
View larger version (69K):
[in this window]
[in a new window]
[Download PowerPoint slide]
  		Fig. 3 Binding site of HPA complexed with cancer antigens. (A) Hydrogen bonding scheme for Tn antigen ({alpha}GalNAc-Ser) binding. (B) Connolly surface of this binding site. (C) and (D) Same representation for Forssman antigen binding ({alpha}GalNAc1-3GalNAc).

 

View this table:
[in this window]
[in a new window]

  		Table III Contact distances (Å) between HPA and ligands

 
Similarly, in the HPA/Forssman complex, the disaccharide extends its reducing extremity out of the trimer surface in a conformation that is compatible with longer ligand binding (Figure 3C and 3D). The conformation of the disaccharide ({Phi}(O5–C1–O1–C3') = 81°, {Psi}(C1–O1–C3'–C4') = 100°) is slightly different to the predicted lower energy minimum ({Phi} = 80°, {Psi} = 80°) (Imberty et al. 1994Go) but belongs to the same conformational family, as does the Forssman disaccharide previously observed interacting with the legume lectin from D. biflorus ({Phi} = 88°, {Psi} = 70°) (Hamelryck et al. 1999Go). In the HPA/Forssman complex, the nonreducing GalNAc establishes the same hydrogen bond network as in the HPA/Tn complex. Only the conformation of the exocyclic group at C5 displays some variations. The second GalNAc residue does not form any hydrogen bonds to the protein. Nevertheless, the hydrophobic face of this residue, i.e., the CH moieties at C4 and C5, makes van der Waals contacts with His84, thus giving His84 an important role in configuring the HPA binding properties; it prevents the binding of compounds with equatorial substituents at C1. This, therefore, provides the binding preference for GalNAc residues with an alpha configuration and also favors hydrophobic interactions with aglycon substituents, rationalizing the higher affinity reported for the Forssman and Tn antigens, when compared to GalNAc monosaccharides (Wu and Sugii 1991Go).

The ability of HPA to agglutinate red cells from individuals with blood group A phenotype (Hammarström and Kabat 1971Go) can also be rationalized from the crystal structure of the HPA/Forssman antigen complex. The binding of blood group A epitope ({alpha}GalNAc1-3[{alpha}Fuc1-2]Gal) can occur with the currently observed orientation of GalNAc in the binding site. A fucose residue branched on position 2 of the reducing galactose will be at the same location as the N-acetyl group in reducing GalNAc for the Forssman disaccharide and the binding properties will not be affected.


   Conclusions
Top
 Abstract
 Introduction
 Results and discussion
 Conclusions
Funding
 References
 
The current absence of progress in breast and colon cancer treatment is due to our lack of knowledge of the underlying mechanisms of metastasis that lead to secondary tumor deposits. HPA is widely used in metastasis research, because of its specificity for cancer cells in the very early stages of the metastatic process, although the molecular basis of the interaction with cancer epitopes is not yet well understood. The structures presented here thus provide for the first time an explanation of the high specificity of this lectin for two cancer associated antigens, and should guide the development of new engineered markers that could be used in cancer research and as diagnostic tools.

Materials
Free and biotinylated H. pomatia agglutinin (HPA) were purchased from Sigma and Vector (Burlingame, CA). Monosaccharide and antigens were purchased from Sigma and Dextra Laboratories (Reading, UK)

Labeling of cancer cells
The colon cancer HT29 cell line was obtained from Dr Corinne Albiges-Rizo (INSERM U823). The cells were maintained in DMEM medium (Invitrogen Carlsbad, CA) supplemented with 10% heat-inactivated fetal calf serum, 4.5 g/L glucose, 100 units/mL penicillin (Invitrogen), and 100 µg/mL streptomycin (Invitrogen) and kept at 37°C in a 5% CO2 humidified atmosphere. Cells were plated at mid-confluency on cover slips in 12-well plates and fixed in 2% paraformaldehyde in phosphate buffered saline (PBS), pH 7.4, for 5 min at room temperature. After two washes, endogeneous peroxydases were quenched by incubating cells in 3% v/v hydrogen peroxide in water for 20 min. Non specific interactions were minimized by saturating wells in PBS containing 5% (w/v) bovine serum albumin, during 30 min. The cells were then incubated with different concentrations of biotinylated HPA solution (500 µL), for 30 min. After the lectin binding step, the cells were incubated with horseradish peroxidase-labeled streptavidin (Sigma) diluted at 1:1000, for 30 min, and subsequently incubated with diaminobenzidine-HCl (0.7 mg/mL) and hydrogen peroxide (3% v/v). Cells were counterstained using fast nuclear red and cover slips were mounted with Moeviol and examined on a BX41 Olympus microscope. Unless otherwise specified, all solutions were made in PBS containing 3% (w/v) serum albumin bovine and each step was followed by three washes in PBS.

Other cancer cell lines were obtained from the ATCC or were kindly provided by Dr L. Poulain (Centre François Baclesse, France). Labeling of HPA by Cy5 was performed using the Cy5 monofunctional dye ester-kit provided by Amersham. Cells were fixed as previously, rinsed in PBS, and incubated for 30 min at room temperature with 10 µg/mL cy5-labeled HPA. After rinsing, nuclei were stained with 5 µM Hoechst 33342, and the cover slips were inverted onto glass slides using Mowiol (Calbiochem, San Diego, CA) mounting medium. The slides were observed with a confocal laser scanning microscopy (CLSM) (LSM510, Zeiss, France).

Crystallization experiments
Crystallization trials were performed with Hampton crystallization screens I and II (Hampton Research, Laguna Niguel, CA). After optimization, crystals were obtained using the hanging drop method with precipitation solution containing lithium sulfate (2.0 M) and ammonium sulfate (3.5 M) in sodium citrate buffer (1.5 M, pH 6.5). Drops were made of an equal volume of reservoir solution and protein solution at 10 mg/mL with ligand at 3-fold excess in molarity.

Crystals were cryocooled at 100 K, after soaking them for the shortest possible time in precipitant solution with 25% PEG 3000 and 25% glycerol added. Data images were recorded on an ADSC Q4R CCD detector (Quantum Corp, Il, USA) at beamline ID14-2 at the ESRF (Grenoble, France). Diffraction images were processed using MOSFLM (Leslie 1992Go) and intensities were scaled and truncated to structure factors using the CCP4 (1994)Go programs SCALA and TRUNCATE.

Structure determination
The structure of HPA/GalNAc complex (PDB code 2CCV) was used as the search model for molecular replacement for the Tn and Forssman complexes with the use of MOLREP (Vagin and Teplyakov 1997Go). In each complex, the few missing amino acids and all sugar residues clearly defined in density were positioned manually using the O software (Jones et al. 1991Go). Refinement cycles with Refmac (Murshudov et al. 1997Go), including further automatic water molecule placement using ARP/wARP (Perrakis et al. 1999Go), manual rebuilding with O resulted in final models with refinement statistics listed in Table II. Stereochemical checks were performed with the PROCHECK program (Laskowski et al. 1993Go). All graphical representations have been performed with the Sybyl program (Tripos Inc, Saint-Louis) and the MOLCAD software (Waldherr-Teschner et al. 1992Go).


   Funding
Top
 Abstract
 Introduction
 Results and discussion
 Conclusions
 Funding
References
 
French Association ARC; La Ligue contre le Cancer to J-F.S.


   Acknowledgements
 
We thank the ESRF, Grenoble, for access to synchrotron data collection facilities.


   Footnotes
 
2 These authors contributed equally to the work. Back

3 Present address: AFMB-CNRS, 31 Chemin Joseph Aiguier, F-13402, Marseille cedex 20, France. Back


   Abbreviations
 
{alpha}GalNAc, {alpha}-D-N-acetylgalactosamine; HPA, Helix pomatia agglutinin; SCID, severe combined immuno deficient


   References
Top
 Abstract
 Introduction
 Results and discussion
 Conclusions
 Funding
 References
 
Brooks SA. The involvement of Helix pomatia lectin (HPA) binding N-acetylgalactosamine glycans in cancer progression. Histol Histopathol (2000) 15:143–158.[Web of Science][Medline]

Brooks SA, Hall DM, Buley I. GalNAc glycoprotein expression by breast cell lines, primary breast cancer and normal breast epithelial membrane. Br J Cancer (2001) 85:1014–1022.[CrossRef][Web of Science][Medline]

Brooks SA, Leathem AJ. Expression of N-acetyl galactosaminylated and sialylated glycans by metastases arising from primary breast cancer. Invasion Metastasis (1998) 18:115–121.[CrossRef][Web of Science][Medline]

Brooks SA, Wilkinson D. Validation of a simple avidin-biotin detection method for Helix pomatia lectin (HPA) binding as a prognostic marker in cancer. Acta Histochem (2003) 105:205–212.[CrossRef][Web of Science][Medline]

Collaborative Project Number 4 (CCP4). The CCP4 suite: Programs for protein crystallography. Acta Crystallogr (1994) D50:760–763.[Web of Science]

Dennis JW, Granovsky M, Warren CE. Glycoprotein glycosylation and cancer progression. Biochim Biophys Acta (1999) 1473:21–34.[Medline]

Dwek MV, Ross HA, Leathem AJ. Proteome and glycosylation mapping identifies post-translational modifications associated with aggressive breast cancer. Proteomics (2001) 1:756–762.[CrossRef][Web of Science][Medline]

Feizi T. Demonstration by monoclonal antibodies that carbohydrate structures of glycoproteins and glycolipids are onco-developmental antigens. Nature (1985) 314:53–57.[CrossRef][Medline]

Hakomori S. Tumor-associated carbohydrate antigens. Annu Rev Immunol (1984) 2:103–126.[CrossRef][Web of Science][Medline]

Hamelryck TW, Loris R, Bouckaert J, Dao-Thi MH, Strecker G, Imberty A, Fernandez E, Wyns L, Etzler ME. Carbohydrate binding, quaternary structure and a novel hydrophobic binding site in two legume lectin oligomers from Dolichos biflorus. J Mol Biol (1999) 286:1161–1177.[CrossRef][Web of Science][Medline]

Hammarström S, Kabat EA. Purification and characterization of a blood-group A reactive hemagglutinin from the snail Helix pomatia and a study of its combining site. Biochemistry (1969) 8:2696–2705.[CrossRef][Medline]

Hammarström S, Kabat EA. Studies on specificity and binding properties of the blood group A reactive hemagglutinin from Helix pomatia. Biochemistry (1971) 10:1684–1692.[CrossRef][Medline]

Hammarström S, Westoo A, Bjork I. Subunit structure of Helix pomatia A hemagglutinin. Scand J Immunol (1972) 1:295–309.[CrossRef][Medline]

Imberty A, Casset F, Gegg CV, Etzler ME, Pérez S. Molecular modelling of the Dolichos biflorus seed lectin and its specific interactions with carbohydrates: alpha-D-N-acetyl-galactosamine, Forssman disaccharide and blood group A trisaccharide. Glycoconj J (1994) 11:400–413.[CrossRef][Web of Science][Medline]

Jones TA, Zou JY, Cowan SW, Kjeldgaard M. Improved methods for the building of protein models in electron density maps and the location of errors in these models. Acta Crystallogr (1991) A47:110–119.[Web of Science][Medline]

Laack E, Nikbakht H, Peters A, Kugler C, Jasiewicz Y, Edler L, Hossfeld DK, Schumacher U. Lectin histochemistry of resected adenocarcinoma of the lung: Helix pomatia agglutinin binding is an independent prognostic factor. Am J Pathol (2002) 160:1001–1008.[Abstract/Free Full Text]

Laskowski RA, MacArthur MW, Moss DS, Thornton JM. PROCHECK: A program to check the stereochemical quality of protein structures. J Appl Crystallogr (1993) 26:283–291.[CrossRef][Web of Science]

Leathem AJ, Brooks SA. Predictive value of lectin binding on breast cancer recurrence and survival. Lancet (1987) 1:1054–1056.[CrossRef][Web of Science][Medline]

Leslie AGW. Recent changes to the MOSFLM package for processing film and image plate data. (1992) Joint CCP4 + ESF-EAMCB Newsletter on Protein Crystallography No. 26.

Mitchell BS, Schumacher U. The use of the lectin Helix pomatia agglutinin (HPA) as a prognostic indicator and as a tool in cancer research. Histol Histopathol (1999) 14:217–226.[Web of Science][Medline]

Murshudov GN, Vagin AA, Dodson EJ. Refinement of macromolecular structures by the maximum-likelihood method. Acta Crystallogr (1997) D53:240–255.

Perrakis A, Morris R, Lamzin VS. Automated protein model building combined with iterative structure refinement. Nat Struct Biol (1999) 6:458–463.[CrossRef][Web of Science][Medline]

Sanchez JF, Lescar J, Chazalet V, Audfray A, Gagnon J, Alvarez R, Breton C, Imberty A, Mitchell EP. Biochemical and structural analysis of Helix pomatia agglutinin (HPA): A hexameric lectin with a novel fold. J Biol Chem (2006) 281:20171–20180.[Abstract/Free Full Text]

Schumacher U, Adam E. Lectin histochemical HPA-binding pattern of human breast and colon cancers is associated with metastases formation in severe combined immunodeficient mice. Histochem J (1997) 29:677–684.[CrossRef][Web of Science][Medline]

Springer GF. Immunoreactive T and Tn epitopes in cancer diagnosis, prognosis, and immunotherapy. J Mol Med (1997) 75:594–602.[CrossRef][Web of Science][Medline]

Vagin A, Teplyakov A. MOLREP: An automated program for molecular replacement. J Appl Crystallogr (1997) 30:1022–1025.[CrossRef][Web of Science]

Waldherr–Teschner M, Goetze T, Heiden W, Knoblauch M, Vollhardt H, Brickmann J. MOLCAD —Computer Aided Visualization and Manipulation of Models in Molecular Science. In: Advances in Scientific Visualization—Post FH, Hin AJS, eds. (1992) Heidelberg: Springer. 58–67.

Wu AM, Sugii S. Coding and classification of D-galactose, N-acetyl-D-galactosamine, and ß-D-Galp-[1-3(4)]-ß-D-GlcpNAc, specificities of applied lectins. Carbohydr Res (1991) 213:127–143.[CrossRef][Web of Science]


Add to CiteULike CiteULike   Add to Connotea Connotea   Add to Del.icio.us Del.icio.us    What's this?



This Article
Right arrow Abstract Freely available
Right arrow FREE Full Text (PDF) Freely available
Right arrow All Versions of this Article:
17/10/1077    most recent
cwm077v1
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in ISI Web of Science
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Add to My Personal Archive
Right arrow Download to citation manager
Right arrow Search for citing articles in:
ISI Web of Science (2)
Right arrowRequest Permissions
Right arrow Disclaimer
Google Scholar
Right arrow Articles by Lescar, J.
Right arrow Articles by Imberty, A.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Lescar, J.
Right arrow Articles by Imberty, A.
Social Bookmarking
Add to CiteULike   Add to Connotea   Add to Del.icio.us  
What's this?