[Cloning and characterization of cDNA for DRPLA interacting protein].

Dentatorubral-pallidoluysian atrophy (DRPLA) is associated with CAG repeat expansion. While the DRPLA gene is ubiquitously expressed, neuron death occurs in specific area of the brain, predicting that the DRPLA protein interacts with other proteins, which may play a role in the pathogenesis. We isolated a DRPLA binding protein with a yeast two-hybrid system, and identified it to be a human homologue of insulin receptor substrate protein of 53 kDa (IRSp53). The binding of the DRPLA protein with IRSp53 was ascertained by co-immunoprecipitation, and colocalization. A proline-rich region near polyglutamine of the DRPLA protein and the SH3 domain of IRSp53 were involved in the binding. Extended polyglutamine significantly reduced the binding ability in yeast cells.