Cloning and identification of a novel binding protein of CD2 cytoplasmic domain

In order to understand why CD2 has a dual action of transduction of activation or apoptosis signals in T cells under different experimental conditions, we employed a yeast two-hybrid system to look for a binding protein of the cytoplasmic domain of CD2 which may be involved in this issue. A human T cell cDNA library was screened by a cDNA encoding the cytoplasmic domain of CD2 (Thr211-Gln336). The specificity of protein-protein interaction was verified by co-immunoprecipitation. The binding protein obtained, designated CD2cBP, was found to be homologous tov-fos transformation effector protein (Fte-1). As Fte-1 plays a role in cell transformation, growth, protein synthesis and protein-import into mitochondria, this result suggests that CD2cBP may be putatively involved in CD2-mediated signaling.