Phosphorylation Reduces the Mechanical Stability of the α‐Catenin/ β‐Catenin Complex

The α‐catenin/β‐catenin complex serves as a critical molecular interface involved in cadherin–catenin‐based mechanosensing at the cell–cell adherence junction that plays a critical role in tissue integrity, repair, and embryonic development. This complex is subject to tensile forces due to internal actomyosin contractility and external mechanical micro‐environmental perturbation. However, the mechanical stability of this complex has yet to be quantified. Here, we directly quantified the mechanical stability of the α‐catenin/β‐catenin complex and showed that it has enough mechanical stability to survive for tens to hundreds of seconds within physiological level of forces up to 10 pN. Phosphorylation or phosphotyrosine‐mimetic mutations (Y142E or/and T120E) on β‐catenin shorten the mechanical lifetime of the complex by tens of fold over the same force range. These results provide insights into the regulation of the α‐catenin/β‐catenin complex by phosphorylation.