inhibition of co-expressed DIPs and Dprs shapes neural development.

In , two interacting adhesion protein families, Dprs and DIPs, coordinate the assembly of neural networks. While intercellular DIP/Dpr interactions have been well characterized, DIPs and Dprs are often co-expressed within the same cells, raising the question as to whether they also interact in . We show, in cultured cells and that DIP-α and DIP-δ can interact in with their ligands, Dpr6/10 and Dpr12, respectively. When co-expressed in with their cognate partners, these Dprs regulate the extent of binding, presumably through competitive interactions. We demonstrate the neurodevelopmental effects of inhibition in fly motor neurons and in the mushroom body. We further show that a long disordered region of DIP-α at the C-terminus is required for but not interactions, likely because it alleviates geometric constraints on binding. Thus, the balance between and interactions plays a role in controlling neural development.