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Previous Article | Next Article 
Molecular and Cellular Biology, November 2003, p. 7965-7972, Vol. 23, No. 22
0270-7306/03/$08.00+0 DOI: 10.1128/MCB.23.22.7965-7972.2003
Copyright © 2003, American Society for Microbiology. All Rights Reserved.
Division of Dermatology, Washington University Medical School, St. Louis, Missouri 63110
Received 28 April 2003/ Returned for modification 21 July 2003/ Accepted 4 August 2003
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ABSTRACT |
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INTRODUCTION |
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Coimmunoprecipitation experiments have revealed two types of E-cadherin homodimers potentially important for cadherin-based adhesion (8, 20, 24). In these dimers cadherin molecules align in a lateral (e.g., they both belong to the same cell) or adhesive orientation. It is possible that these dimers represent detergent-resistant portions of larger multimeric cadherin complexes. Nevertheless, a number of observations suggest that the adhesive dimers are the simplest structural units of cadherin-mediated adhesion. Our previous data showed that under standard culture conditions the adhesive dimers appear to be a dominant form (14). The adhesive dimers immediately dissociate, however, and the lateral dimers become prevalent after the calcium concentration drops below 100 µM. This change is accompanied by the complete disruption of adherens junctions. An E-cadherin lacking either calcium-binding sites or its intracellular catenin-binding region can establish neither cell-cell adhesion nor adhesive dimers. In contrast, the E-cadherin point mutation D155A simultaneously increases both the amount of adhesive dimers and the recruitment of the E-cadherin into junctional sites (16). Finally, the amino-terminal domain of E-cadherin determines the specificity of both cell-cell adhesion and cadherin dimerization (13). Whether lateral dimers have any function in cell-cell adhesion is not so clear. Although adhesive and lateral dimers are remarkably stable in cell lysates, they have been suggested to be very dynamic in living cells. We have proposed that the continuous formation of short-lived adhesive dimers within cell-cell junctions is a basic mechanism of cadherin-mediated adhesion (14). To further evaluate this hypothesis, it is necessary to characterize in detail the binding sites involved in adhesive and lateral cadherin dimerization.
The classic cadherin extracellular region consists of five EC domains (numbered from the outermost N-terminal domain). Successive EC domains, each of which is folded into a seven-stranded (A to G) ß-sandwich (5, 18, 25) are interconnected by three calcium ions. Structural studies suggest several alternative models for cadherin dimers. According to the "strand dimer" model, cadherin adhesive dimerization is driven by the reciprocal insertion of the EC1 domain residue Trp156 (amino acid numbering as in reference 6) located at the ß-strand A into the hydrophobic pocket of the paired EC1 domain (5, 25). Controversy remains, however, regarding whether such Trp156-dependent strand dimer interaction does occur on the cell surface or if it is caused solely by the crystallization process (discussed in references 11, 15, and 17). Point mutagenesis experiments did show that the Trp156 residue is indispensable for adhesive dimerization (8), as well as for the adhesive activity of classic cadherins (29). One can argue, however, that the Trp156 mutation induces some conformational abnormalities in the EC1 domain and/or affects lateral cadherin dimerization, thereby precluding E-cadherin from adhesive dimerization which is mediated by a distinct mechanism. At least three alternative models of intercadherin interactions which, in theory, may produce lateral and/or adhesive dimers detected in coimmunoprecipitation assay are suggested. These models include: (i) cadherin dimerization via the "adhesive" interface of the EC1 domain containing His233 and Val235 residues (25); (ii) cadherin dimerization via EC1/EC2 calcium-binding sites (18, 21); and (iii) interactions between antiparallel cadherin molecules along their full length (7, 27). This uncertainty in the structure of adhesive and lateral dimers precludes an understanding of cadherin-based adhesion.
In the present study a new assay, a cysteine scanning mutagenesis of E-cadherin in conjunction with cysteine-specific cross-linking, was applied to study cadherin dimerization on the surface of epithelial A-431 cells. These experiments revealed adhesive and lateral cadherin dimers with features very similar to those obtained previously for cadherin dimers in a coimmunoprecipitation assay. Notably, this new approach confirmed that under standard culture conditions adhesive dimers are a dominant form. Furthermore, our experiments unexpectedly indicated that a single interface mediates both adhesive and lateral dimerization. Analysis of the cross-linking efficiency of various cysteine mutants suggested that this interface represents the strand dimer interface described elsewhere (5, 25). The coexistence of the structurally identical adhesive and lateral dimers on the cell surface suggests high flexibility of the extracellular cadherin region.
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MATERIALS AND METHODS |
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Transfection, growth, and immunofluorescence microscopy of human A-431 cells were done as described previously (8). The following antibodies were used: anti-E-cadherin,clones HECD-1 (Zymed Laboratories) and C20820 (Transduction Laboratories); anti-myc, clone 9E10 (provided by R. Kopan, Washington University Medical School, St. Louis, Mo.); and anti-flag M2 (Sigma).
The immunoprecipitation assay was done as described previously (8). In brief, the confluent monolayer was washed and extracted at 4°C with 1.5 ml of immunoprecipitation lysis buffer (50 mM Tris-HCl [pH 7.4], 150 mM NaCl, 0.5 mM AEBSF [4-(2-aminoethyl)-benzenesulfonyl fluoride], 2 mM EDTA, 1% NP-40). NP-40-insoluble material was removed by centrifugation at 100,000 x g for 1 h. The lysates were subjected to immunoprecipitation by subsequent incubations with anti-myc antibody and protein A-Sepharose. Resulting precipitates were either boiled directly in sodium dodecyl sulfate (SDS)-gel sample buffer or cross-linked (see below).
The homobifunctional chemical cross-linker BM[PEO]3 with a spacer arm length of 1.47 nm (Pierce) was used for cell surface labeling. Confluent cultures were washed with phosphate-buffered saline containing 0.5 mM CaCl2 (PBS-C). Each plate was then incubated for 10 min at room temperature in PBS-C containing a 1 mM concentration of cross-linker. The reaction was stopped by washing the cells with PBS containing 10 mM dithiothreitol. Surface-cross-linked and control cells were either solubilized directly in the SDS-gel sample buffer or subjected to immunoprecipitation. For immunoprecipitation, cells were extracted in IP-SDS buffer (50 mM Tris-HCl [pH 7.4], 150 mM NaCl, 0.5 mM AEBSF, 2 mM EDTA, 1% NP-40, 0.2% SDS) after cross-linking and then immunoprecipitated as described above. Aliquots of the total cell extracts or immunoprecipitates were separated by SDS-5% polyacrylamide gel electrophoresis and then analyzed by immunoblotting as described previously (8).
To cross-link proteins in the anti-myc immunoprecipitates, the protein A-beads were incubated for 5 min at room temperature after the final wash in PBS-T (PBS, 0.5% Triton X-100) with 100 µl of 1 mM BM[PEO]3 (in PBS-T). The reaction was stopped by adding an equal volume of PBS-T containing 10 mM dithiothreitol. The beads were then collected by centrifugation and boiled in an SDS-gel sample buffer.
In some experiments cell surface proteins were biotinylated with EZ-link PEO-Maleimide Activated Biotin (Pierce). Cells were washed two times with PBS-C and then incubated for 5 min with a biotinylation reagent solubilized immediately before use in the same buffer. Cells were then immunoprecipitated with anti-myc antibody as described above. Biotinylated proteins were visualized with streptavidin-horseradish peroxidase conjugate.
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RESULTS |
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In the next step, the residues Leu175, Val176, Gln177, and Lys179, located at EC1 strand B and which protrude between two paired EC1 domains in the strand dimer interface model (25) (Fig. 1A), were individually substituted for cysteine. The resulting Ec1M mutants were stably expressed in A-431 cells and analyzed as described for Ec1M-C163A. Again, no abnormalities either in the subcellular distribution of the mutants or in the amounts of the adhesive dimers they formed (Fig. 1B) were found. When the corresponding cells were exposed to BM[PEO]3, all of these mutants, in contrast to Ec1M and Ec1M-C163A, formed a cross-linked product with a molecular mass of 
220 kDa (Fig. 1C). The mutant Ec1M-C163A/K179C also produced a unique 280-kDa complex. The nature of this complex remains unknown.
The mutant Ec1M-C163A/V176C was studied in detail because it produced the highest level of the 220-kDa product. Figure 2A shows that this product forms equally well at both normal and low calcium concentrations, suggesting that all of its components may belong to the same cell. Inactivation of the EC1/EC2 calcium-binding sites by the additional mutation E165A did not abolish this product formation (Fig. 2A, lane E165A). In contrast, point mutation W156A completely inactivated this reaction (lane W156A). These experiments suggested that the 220-kDa product may correspond to the Trp156-dependent lateral dimer, which has been detected by coimmunoprecipitation assay and which has exactly the same features (8).
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Adhesive and lateral dimers have similar structures. We next studied whether adhesive and lateral dimers revealed by cross-linking experiments have similar structures. For this purpose, we compared the relative amounts of cross-linked lateral and adhesive dimers in cells producing various Cys mutants. Figure 3A (compare with Fig. 1C) shows that after calcium depletion, each mutant produced the same amount of dimers as in a standard culture. It indicated that the structure of lateral dimers cross-linked at low calcium and that of dimers present in standard conditions are very similar. To reveal exclusively adhesive dimers, the cells expressing a myc-tagged mutant were cocultured with the cells expressing the same mutant tagged with the flag epitope. Anti-myc immunoprecipitation and anti-flag analysis of the immunoprecipitates (Fig. 3B) showed that the relative amount of cross-linked adhesive dimers matched that of lateral dimers. These data suggested that the same binding site is responsible for the formation of lateral dimers in low calcium and adhesive dimers in standard conditions.
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As an alternative attempt to reveal a function of the Ca2+-binding interface, we constructed two additional mutants: Ec1M-Q255A and Ec1M-N297A. According to the calcium site model, the backbone carbonyl oxygen atoms of these residues coordinate calcium ions, while their side chains participate in dimerization. Therefore, we proposed that these point mutations would not change calcium binding but may have a dramatic effect on dimer formation. Expression of these mutants in A-431 cells was unable to reveal any specific effect of these mutations on the property of E-cadherin or cellular phenotype (not shown).
Identity of the dimers revealed by coimmunoprecipitation and site-specific cross-linking assays. The E-cadherin dimerization detected by two alternative approaches—the BM[PEO]3 cross-linking of the living cells and the coimmunoprecipitation of myc/flag-tagged cadherins from cell lysates—shares similar features. In both cases dimerization is Trp156 dependent. Under standard culture conditions adhesive dimerization prevails over lateral dimerization, but the latter dimerization mode becomes dominant after calcium depletion. These similarities suggest that these two different approaches in fact detect the same cadherin-cadherin interaction. To further clarify this important issue, we studied whether E-cadherin cysteine mutants can be cross-linked by BM[PEO]3 in the anti-myc immunoprecipitates. Figure 6A shows that cross-linking of such an immunoprecipitate obtained from Ec1M- C163A/V176C-expressing cells results in formation of the same 220-kDa cross-linking product. Importantly, the cross-linking of this mutant in the immunoprecipitate and on the cell surface produced exactly the same (relative to the monomeric form) amounts of the 220-kDa product. As expected, the formation of the 220-kDa product was completely abolished after point mutation W156A (Fig. 6B). A high specificity of dimer cross-linking in vitro was further indicated by the fact that the mutants Ec1M-C163A/T229C and Ec1M-C163A/F231C cannot be cross-linked either on the cell surface (Fig. 5B) or in the immunoprecipitates (Fig. 6B). Taken together, these experiments demonstrated that E-cadherin dimers which can be cross-linked on the cell surface are stable during cell solubilization and in vitro manipulations.
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DISCUSSION |
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E-cadherin molecule contains a single unpaired cysteine, Cys163, located in close proximity to Trp156 (5, 19). We found that the sulfhydryl group of this cysteine cannot be efficiently biotinylated in standard culture conditions, apparently because it is buried within the EC1 hydrophobic core (18, 21). However, since this cysteine can be biotinylated after calcium depletion, it was replaced with Ala. The resulting E-cadherin mutant (Ec1M-C163A) showed no differences from its parent molecule, Ec1M, in subcellular distribution, binding to catenins (not shown), or adhesive and lateral dimerization. However, it could not be biotinylated, even at low calcium concentrations. Therefore, this mutant is ideal for site-specific cross-linking experiments.
In order to reveal cadherin dimers using BM[PEO]3 cross-linking, novel sulfhydryl groups were introduced to the strand B of the Ec1M-C163A mutant by point mutations L175C, V176C, Q177C, or K179C. The corresponding residues were selected because their side chains are exposed in the strand dimer interface described by Shapiro et al. (25). These substitutions did allow us to cross-link E-cadherin dimers. Notably, the major features of these dimers and those previously detected by coimmunoprecipitation assay (8, 14) are essentially the same. In both cases, (i) the combined amount of adhesive and lateral dimers is calcium independent; (iii) all dimers are lateral in a low calcium concentration, whereas adhesive dimers become a dominant form in standard calcium concentrations; and (iii) both the adhesive and lateral dimers require the integrity of Trp156 residue. Such prominent similarities between cadherin dimers detected in coimmunoprecipitation and cross-linking assays suggest that these two independent approaches reveal the same type of cadherin dimerization. This conclusion is further supported by the fact that cell extraction with the immunoprecipitation buffer and the following immunoprecipitation did not affect the pool of cadherin dimers available for cross-linking.
The V176C mutation resulted in the most efficient cross-linking of cadherin dimers. Perhaps this was due to the fact that in the strand dimer model the side chains of Val176 are facing each other (see Fig. 1A). Several additional considerations allow us to discard the possibility that the cross-linked products correspond to other types of dimers revealed by crystallography. It would be very improbable that cadherin dimerization in cross-linked dimers is mediated by the His233/Val235-containing "adhesive" interface discovered in the N-cadherin EC1 domain crystals (25). First, since the B strands in the dimer organized by this interface are located on opposite surfaces of the dimer, it is unlikely that they can be cross-linked in our experiments. Second, this interface was not evident in experiments with three different cysteine mutants specifically designed to verify this interaction. Therefore, the data obtained by our site-specific cross-linking assay is consistent with previous mutational and immunochemical analyses (12, 16, 26) which failed to reveal the function of this interface in cadherin-cadherin interactions.
The Trp156 but not Ca2+ dependence of the cross-linked dimers appears to exclude that they are organized according to the calcium-binding site model reported by Nagar et al. (18) and Pertz et al. (21). Moreover, all our attempts to reveal the calcium-binding site model by cysteine mutagenesis of the EC2 domain using this model as a blueprint failed. There are several explanations for why calcium-dependent cadherin dimerization documented for EC1/EC2 fragments of E-cadherin in crystals (18, 21) and in solution (11) was not detected in our cross-linking or in our coimmunoprecipitation assays. It is possible that calcium-binding site-mediated dimerization is more favorable than Trp156-dependent dimerization for some cadherin fragments. The presence of a foreign methionine at the E-cadherin N terminus may further have hampered strand dimer interaction in experiments reported by Haussinger et al. (11). This interpretation is supported by our recent work showing that such additional methionine prevents the assembly of Trp156-dependent E-cadherin dimers (16). Furthermore, E-cadherin extended from the cellular surface may utilize some specific mechanisms facilitating the assembly of strand dimers but not of calcium site dimers. An alternative possibility is that calcium site dimers, while present on the cell surface, cannot be detected by both of our assays: they are not stable during immunoprecipitation, and their lifetime is much shorter than the time needed for the cross-linking reaction. However, we regard the latter possibility as less likely since the point mutations Q255A and N297A, which according to the calcium-binding site model would affect the dimerization interface, did not change E-cadherin properties.
Our site-specific cross-linking experiments indicate that the same interface mediates both adhesive and lateral cadherin dimerization. Otherwise, it is difficult to explain the fact that neither one of the four cysteine strand B mutants allows preferential cross-linking of either adhesive or lateral dimers. The parallel alignment of two cadherin molecules in the adhesive dimer is also evident from the experiments with hybrid dimers consisting of strand B and strand G mutants. Our previous observation that the same set of mutations equally affects both adhesive and lateral dimers (16) further supports their structural identity. Therefore, our data, in complete agreement with a recent structural study (5), suggest that at a standard calcium concentration a curve of extracellular cadherin regions allows the EC1 domain to form an adhesive dimer via a strand dimer interface. Continual assembly-disassembly of such adhesive dimers within cadherin clusters may establish dynamic adhesive links between apposing cells (14). Whether cadherin clustering is achieved by catenins or by additional intercadherin interactions—as proposed by Boggon et al. (5)—remains to be determined.
The immediate assembly of lateral and the concomitant disassembly of adhesive dimers after calcium removal might be caused by two factors: (i) the short lifetime of preassembled adhesive dimers (14) and (ii) a change in the overall extracellular cadherin conformation, affecting a correct presentation of the EC1 domain and thereby inhibiting adhesive but permitting lateral dimerization. However, lateral Trp156-dependent dimerization (heterodimerization of two classic cadherins, in particular) was clearly documented in many experiments even in a standard calcium concentration (13, 20, 24). These observations indicate that at a high calcium concentration the cadherin extracellular region may also have some flexibility sufficient to form both types of dimers using the same dimer interface (see Fig. 5D). In agreement with this hypothesis, previous electron microscopic analysis demonstrated that, in the presence of 2 mM Ca2+, the cadherin ectodomain represents flexible rods (2, 22). Furthermore, it has been proposed that the flexibility of the cadherin ectodomain is necessary for adhesive interactions between apposing surfaces which are in constant motion (2). The molecular mechanisms and extent of this flexibility remain to be determined. Notably, an E-cadherin lacking a catenin-binding site preferentially forms lateral dimers (8). Therefore, catenins might have an important function in retaining the cadherin extracellular conformation required for adhesive dimerization. These catenin-induced changes in the cadherin extracellular region may also control the lifetime of adhesive dimers.
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ACKNOWLEDGMENTS |
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We thank J. Klingelhofer (Institute of Cancer Biology, Denmark) for help in the preparation of Fig. 5D and V. Mazurov for technical assistance in some experiments.
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FOOTNOTES |
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REFERENCES |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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2. Becker, J. W., H. P. Erickson, S. Hoffman, B. A. Cunningham, and G. M. Edelman. 1989. Topology of cell adhesion molecules. Proc. Natl. Acad. Sci. USA 86:1088-1092.
3. Bibert, S., M. Jaquinod, E. Concord, C. Ebel, E. Hewat, C. Vanbelle, P. Legrand, M. Weidenhaupt, T. Vernet, and D. Gulino-Debrac. 2002. Synergy between extracellular modules of vascular endothelial cadherin promotes homotypic hexameric interactions. J. Biol. Chem. 277:12790-12801.
4. Blaschuk, O. W., and T. M. Rowlands. 2002. Plasma membrane components of adherens junctions. Mol. Membr. Biol. 19:75-80.[CrossRef][Medline]
5. Boggon, T. J., J. Murray, S. Chappuis-Flament, E. Wong, B. M. Gumbiner, and L. Shapiro. 2002. C-cadherin ectodomain structure and implications for cell adhesion mechanisms. Science 296:1308-1313.
6. Bussemakers, M. J., A. van Bokhoven, S. G. Mees, R. Kemler, and J. A. Schalken. 1993. Molecular cloning and characterization of the human E-cadherin cDNA. Mol. Biol. Rep. 17:123-128.[CrossRef][Medline]
7. Chappuis-Flament, S., E. Wong, L. D. Hicks, C. M. Kay, and B. M. Gumbiner. 2001. Multiple cadherin extracellular repeats mediate homophilic binding and adhesion. J. Cell Biol. 154:231-243.
8. Chitaev, N. A., and S. M. Troyanovsky. 1998. Adhesive but not lateral E-cadherin complexes require calcium and catenins for their formation. J. Cell Biol. 142:837-846.
9. Gumbiner, B. M. 1996. Cell adhesion: the molecular basis of tissue architecture and morphogenesis. Cell 84:345-357.[CrossRef][Medline]
10. Hajra, K. M., and E. R. Fearon. 2002. Cadherin and catenin alterations in human cancer. Genes Chromosomes Cancer 34:255-268.[CrossRef][Medline]
11. Haussinger, D., T. Ahrens, H. J. Sass, O. Pertz, J. Engel, and S. Grzesiek. 2002. Calcium-dependent homoassociation of E-cadherin by NMR spectroscopy: changes in mobility, conformation and mapping of contact regions. J. Mol. Biol. 324:823-839.[CrossRef][Medline]
12. Kitagawa, M., M. Natori, S. Murase, S. Hirano, S. Taketani, and S. T. Suzuki. 2000. Mutation analysis of cadherin-4 reveals amino acid residues of EC1 important for the structure and function. Biochem. Biophys. Res. Commun. 271:358-363.[CrossRef][Medline]
13. Klingelhofer, J., R. B. Troyanovsky, O. Y. Laur, and S. M. Troyanovsky. 2000. Amino-terminal domain of classic cadherins determines the specificity of the adhesive interactions. J. Cell Sci. 113:2829-2836.[Abstract]
14. Klingelhofer, J., O. Y. Laur, R. B. Troyanovsky, and S. M. Troyanovsky. 2002. Dynamic interplay between adhesive and lateral E-cadherin dimers. Mol. Cell. Biol. 22:7449-7458.
15. Koch, A. W., D. Bozic, O. Pertz, and J. Engel. 1999. Homophilic adhesion by cadherins. Curr. Opin. Struct. Biol. 9:275-281.[CrossRef][Medline]
16. Laur, O. Y., J. Klingelhofer, R. B. Troyanovsky, and S. M. Troyanovsky. 2002. Both the dimerization and immunochemical properties of E-cadherin EC1 domain depend on Trp156 residue. Arch. Biochem. Biophys. 400:141-147.[CrossRef][Medline]
17. Leckband, D., and S. Sivasankar. 2000. Mechanism of homophilic cadherin adhesion. Curr. Opin. Cell Biol. 12:587-592.[CrossRef][Medline]
18. Nagar, B., M. Overduin, M. Ikura, and J. M. Rini. 1996. Structural basis of calcium-induced E-cadherin rigidification and dimerization. Nature 380:360-364.[CrossRef][Medline]
19. Ozawa, M., H. Hoschutzky, K. Herrenknecht, and R. Kemler. 1990. A possible new adhesive site in the cell-adhesion molecule uvomorulin. Mech. Dev. 33:49-56.[CrossRef][Medline]
20. Ozawa, M. 2002. Lateral dimerization of the E-cadherin extracellular domain is necessary but not sufficient for adhesive activity. J. Biol. Chem. 277:19600-19608.
21. Pertz, O., D. Bozic, A. W. Koch, C. Fauser, A. Brancaccio, and J. Engel. 1999. A new crystal structure, Ca2+ dependence, and mutational analysis reveal molecular details of E-cadherin homoassociation. EMBO J. 18:1738-1747.[CrossRef][Medline]
22. Pokutta, S., K. Herrenknecht, R. Kemler, and J. Engel. 1994. Conformational changes of the recombinant extracellular domain of E-cadherin upon calcium binding. Eur. J. Biochem. 223:1019-1026.[Medline]
23. Provost, E., and D. L. Rimm. 1999. Controversies at the cytoplasmic face of the cadherin-based adhesion complex. Curr. Opin. Cell Biol. 11:567-572.[CrossRef][Medline]
24. Shan, W.-S., H. Tanaka, G. R. Phillips, K. Arndt, M. Yoshida, D. R. Colman, and L. Shapiro. 2000. Functional cis-heterodimers of N- and R-cadherins. J. Cell Biol. 148:579-590.
25. Shapiro, L., A. M. Fannon, P. D. Kwong, A. Thompson, M. S. Lehmann, G. Grubel, J.-F. Legrand, J. Als-Neilsen, D. R. Colman, and W. A. Hendrickson. 1995. Structural basis of cell-cell adhesion by cadherins. Nature 374:327-337.[CrossRef][Medline]
26. Shimoyama, Y., H. Takeda, S. Yoshihara, M. Kitajima, and S. Hirohashi. 1999. Biochemical characterization and functional analysis of two type II classic cadherins, cadherin-6 and -14, and comparison with E-cadherin. J. Biol. Chem. 274:11987-11994.
27. Sivasankar, S., B. Gumbiner, and D. Leckband. 2001. Direct measurements of multiple adhesive alignments and unbinding trajectories between cadherin extracellular domains. Biophys. J. 80:1758-1768.
28. St. Amand, A. L., and M. W. Klymkowsky. 2001. Cadherins and catenins, Wnts and SOXs: embryonic patterning in Xenopus. Int. Rev. Cytol. 203:291-355.[Medline]
29. Tamura, K., W. S. Shan, W. A. Hendrickson, D. R. Colman, and L. Shapiro. 1998. Structure-function analysis of cell adhesion by neural (N-) cadherin. Neuron 20:1153-1163.[CrossRef][Medline]
30. Tepass, U., K. Truong, D. Godt, M. Ikura, and M. Peifer. 2000. Cadherins in embryonic and neural morphogenesis. Nat. Rev. Mol. Cell. Biol. 1:91-100.[CrossRef][Medline]
31. Troyanovsky, S. M. 1999. Mechanism of cell-cell adhesion complex assembly. Curr. Opin. Cell Biol. 11:561-566.[CrossRef][Medline]
32. Wheelock, M. J., A. P. Soler, and K. A. Knudsen. 2001. Cadherin junctions in mammary tumors. J. Mammary Gland Biol. Neoplasia 6:275-285.
33. Yap, A. S., W. M. Brieher, and B. M. Gumbiner. 1997. Molecular and functional analysis of cadherin-based adherens junctions. Annu. Rev. Cell Dev. Biol. 13:119-146.[CrossRef][Medline]
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