Interaction of the SH2 domain of Fyn with a cytoskeletal protein beta-adducin

Fyn is a Src family tyrosine kinase expressed abundantly in neurons and bel ieved to have specific functions in the brain. To understand the function o f Fyn tyrosine kinase, we attempted to identify Fyn Src homology 2 (SH2) do main-binding proteins from a Nonidet P-40-insoluble fraction of the mouse b rain. beta -Adducin, an actin filament-associated cytoskeletal protein, was isolated by two-dimensional gel electrophoresis and identified by tandem m ass spectrometry. beta -Adducin was tyrosine phosphorylated by coexpression with wild type but not with a kinase-negative form of Fyn in COS-7 cells. Cell staining analysis showed that coexpression of beta -adducin with Fyn i nduced translocation of beta -adducin from the cytoplasm to the periphery o f the cells where it was colocalized with actin filaments and Fyn. These fi ndings suggest that tyrosine-phosphorylated beta -adducin associates with t he SH2 domain of Fyn and colocalizes under plasma membranes.