| Research Abstract |
In order to clarify the signal transduction mechanisms underlying the differentiation-promoting and survival-promoting effects of neurotrophins including NGF and BDNF, we performed the yeast two-hybrid system using the intracellular domains of TrkA and TrkB, the high-affinity receptors of NGF and BDNF, respectively, as the bait protein. We isolated independent 20-30 clones which bind to the intracellular region of TrkA or TrkB, from rat brain cDNA library or mouse, brain cDNA library. From the database search with nucleotide sequences of these clones, we identified seven new proteins involved in the Trk receptor signal. The seven proteins are gephyrin, Rho GTPase activating protein(RhoGAP), nucleoside diphosphate kinase B, nucleoporin 153, nucleoporin p58, κB motif-binding phosphoprotein, and 105kD kinase like protein. Gephyrin, Rho GTPase activating protein(RhoGAP) and nucleoside diphosphate kinase B could bind to the intracellular regions of both TrkA and TrkB, indicating that these three proteins bind to the homology region between TrkA and TrkB. Rho GTPase activating protein(RhoGAP) and two nucleoporins could bind to the intracellular regions of both wild-type TrkA and kinase-defective TrkA. κB motif-binding phosphoprotein and 105kD kinase like protein could bind only to the intracellular regions of kinase-defective TrkA. We are now investigating the binding activities and the functions in the signal transduction mechanism of the seven proteins in neuronal cells.
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