In the first extracellular domain of E-cadherin, heterophilic interactions, but not the conserved His-Ala-Val motif, are required for adhesion.
The classical cadherins, definitive proteins of the cadherin superfamily, are characterized functionally by their ability to mediate calcium-dependent cell aggregation in vitro. To test hypothetical mechanisms of adhesion, we have constructed two mutants of the chicken E-cadherin protein, one with the highly conserved His-Ala-Val (HAV) sequence motif reversed to Val-Ala-His (VAH), the other lacking the first extracellular domain (EC1). The inversion of HAV to VAH has no effect on the capacity of E-cadherin to mediate adhesion. Deletion of EC1 completely eliminates the ability of E-cadherin to mediate homophilic adhesion, but the deletion mutant is capable of adhering heterophilically to both unmutated E-cadherin and to the HAV/VAH mutant. These results demonstrate that the conserved HAV sequence motif is not involved in cadherin-mediated adhesion as has been suggested previously and supports the idea that in the context of the cell surface, cadherin-mediated cell-cell adhesion involves an interaction of EC1 with other domains of the cadherin extracellular moiety and not the "linear zipper" model, which posits trans interactions only between EC1 on apposing cell surfaces.
Renaud-Young
Margaret
M
Department of Biological Sciences, University of Alberta, Edmonton, Alberta T6G 2E9, Canada.
Gallin
Warren J
WJ
D000409:Alanine / Q000737:chemistry; D020816:Amino Acid Motifs; D000818:Animals; D019921:Biotinylation; D015153:Blotting, Western; D015820:Cadherins / Q000737:chemistry* / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D002448:Cell Adhesion; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D002645:Chickens; D006639:Histidine / Q000737:chemistry; D007477:Ions; D051379:Mice; D008856:Microscopy, Fluorescence; D009154:Mutation; D010957:Plasmids / Q000378:metabolism; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D015398:Signal Transduction; D013997:Time Factors; D014162:Transfection; D014633:Valine / Q000737:chemistry; D014981:Xenopus
D015820:Cadherins; D007477:Ions; D006639:Histidine; D014633:Valine; D000409:Alanine; D002118:Calcium