Evidence for synergistic and complementary roles of Bassoon and darkness in organizing the ribbon synapse

► Darkness and Bassoon complementarily organize the ribbon synapse. ► Darkness induces the initial tethering of synaptic ribbons (SRs) to the membrane. ► Bassoon is required for tight anchorage of the SR to the membrane. ► Darkness initiates the basic assembly of ribbon material to a rod-like structure. ► Bassoon facilitates proper assembly of SRs to the full-sized “horseshoe”.