District Inside Of Cd2 Cell Binding Protein Molecular Cloning And Functional Study

CD2 plays an important role in the differentiation, maturation, activation and apoptosis of T lymphocyte. The CD2 cytoplasmic domain contributes in a central way to CD2 function. The roles for the CD2 cytoplasmic domain are signal transduction and modulation of the adhesion function of CD2. In order to elucidate the signaling pathway mediated by CD2 cytoplasmic domain, the following studies were carried out and a series promising results were gotten.1. Yeast two hybrid system was employed to screen a human T cell cDNA library for binding protein of CD2 cytoplasmic domain by using a 'bait ' cDNA encoding the cytoplasmic domain of CD2 (Thr 211-Glu336) amplified from human peripheral blood lymphocytes (PBL). A cDNA encoding CD2 binding protein, designated as CD2cBP, was cloned. A homology study showed that CD2cBP is homologous to v-fos transformation effector (Fte-1).2. It was demonstrated by co-immunoprecipitation in mammlian cells that CD2cBP binds to CD2 cytoplasmic domain specifically.3. By 5'-RACE and RT-PCR, it was confirmed that both CD2cBP and Fte-1 are expressed in human PBL and the leukemia T cell line (Jurkat). The full-length cDNA of Fte-1 was amplified from human PBL.4. It was shown that CD2cBP and Fte-1 could be phosphorylated by activated PKC by phorbel esters PMA and PKC extracted from rat brain. And the phosphorylation could be blocked remarkably by PKC-specific inhibitor.5. Jurkat cells were transiently trasfected with CD2cBP-GFP fusion gene, and it was found that CD2cBP was expressed in cytoplasma and translocated to the cell inner membrane followed by CD2 cross-linking with anti-CD2 antibody, suggesting that the interaction between CD2 cytoplasmic domain and CD2cBP was involved in this process.