1. Different structural strategies for homophilic binding of insect and vertebrate E-cadherins through their ectodomains.
Different structural strategies for homophilic binding of insect and vertebrate E-cadherins through their ectodomains. (A) A proposed model of a folded arrangement of the six consecutive N-terminal extracellular cadherin domains of insect E-cadherin. (B) The general model of a slightly curved, tandem arrangement of the five consecutive extracellular cadherin domains of vertebrate E-cadherin. Only the molecular domains focused on in this work are displayed in color. The extracellular cadherin domains shown in green serve analogously as the determinants of homophilic binding specificities. Yellow dots indicate Ca2+ ions that are inserted into the linker regions of the neighboring extracellular cadherin domains to rigidify the tandem structures of the consecutive extracellular cadherin domains. As an exception, the Ca2+-free EC2–EC3 linker of insect E-cadherin might confer foldability on the consecutive extracellular cadherin domains. The EC2–EC4 region of insect E-cadherins plays a primary role in mediating the homophilic binding specificity, with EC1 playing a supportive role. In addition, the EC1 domain of vertebrate E-cadherin contains a conserved tryptophan residue (W) inserted into the hydrophobic pocket (not depicted) in the EC1 of the partner cadherin.
Shigetaka Nishiguchi et al. J Cell Sci 2016;129:
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