E-CADHERIN ENGAGEMENT STIMULATES TYROSINE PHOSPHORYLATION

Cadherins are cell adhesion molecules concentrated at intercellular ad herens junctions, where they form a multiprotein complex with cytoplas mic catenins. Although cell-cell interactions affect many aspects of c ell behavior, little is known about signaling pathways triggered by ca dherin engagement. We show here that E-cadherin-mediated cell-cell adh esion leads to a rapid increase in tyrosine phosphorylation at sites o f cell-cell contact and that this stimulation of tyrosine phosphorylat ion can be mimicked by aggregation of E-cadherin with antibodies. The proteins that become phosphorylated are distinct from those previously shown to be tyrosine phosphorylated in response to integrin-mediated adhesion and include ras-GAP. We also find that E-cadherin-mediated ty rosine phosphorylation is not required for the assembly of adherens-ty pe junctions.