The N-terminal vinculin-homology 1 (VH1) domain of α-catenin facilitates two exclusive forms, a monomeric form directly bound to β-catenin for linking E-cadherin to F-actin or a homodimer for the inhibition of β-catenin binding. Competition of these two forms is affected by ∼80 N-terminal residues, whose structure is poorly understood. We have determined the structure of the monomeric free form of the αN-catenin VH1 domain and revealed that the N-terminal residues form α1 and α2 helices to complete formation of the N-terminal four-helix bundle. Dynamic conformational changes of these two helices control formation of the β-catenin-bound monomer or unbound homodimer.
Keywords: Adherens junction; Conformational switch; Helix bundle; α-Catenin; β-Catenin.
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