DAP-1, a novel protein that interacts with the guanylate kinase-like domains of hDLG and PSD-95

Background: The human homologue of the Drosophila discs large tumour suppressor protein (hDLG) and closely related proteins such as postsynaptic density protein 95 kDa (PSD-95) are associated with N-methyl-D-aspartate receptors (NMDA-R) and Shaker-type K+ channels, and are thought to be involved in their clustering. Results: We have identified a protein named DAP-1 that binds to the guanylate kinase-like domains of hDLG and PSD-95, DAP-1 was found to associate with hDLG, PSD-95, NMDA-R and adenomatous polyposis coli protein (APC). Furthermore, we found that DAP-l is specifically expressed in the brain and colocalizes with PSD-95 and APC in mouse cerebellum, We also found that DAP-1 is colocalized with PSD-95 and NMDA-R at the synapses in cultured rat hippocampal neurons. Conclusion: Our findings suggest that DAP-1 may play several roles in the molecular organization of synapses and neuronal cell signalling by interacting with hDLG and PSD-95, which in turn are associated with receptors, ion channels and APC.