Regions downstream from the WW domain of dystrophin are important for binding to postsynaptic densities in the brain.

In order to investigate the mechanism of dystrophin localization in the central nervous system (CNS), we generated adenovirus vectors that contained minidystrophin or truncated minidystrophin cDNA. We infected a primary neuronal culture derived from mdx mouse hippocampus with these viruses. Minidystrophin was observed along the plasma membrane as punctate dots or very short segments. In double immunofluorescence staining with anti-dystrophin and anti-postsynaptic density-95 antibodies, we observed that these proteins entirely colocalized. On the other hand, the truncated minidystrophin, which has deleted WW, cysteine-rich and C-terminal domains, was homogenously expressed in cytoplasm, neurites and axons. These findings suggest that a binding site to postsynaptic densities exists in the region extending from the WW domain to the C-terminal domain of dystrophin and that this site is necessary for binding to membrane.