Sophistication shown with InaD, a polypeptide with 5 PDZ domains that regulates phototransduction in Drosophila photoreceptors.  InaD associates through distinct PDZ domains with a calcium channel (TRP); phospholipase C-b and PKC. InaD organizes these proteins into a signaling complex that allows efficient activation of the TRP channel by PKC-b in response to stimulation of rhodopsin and deactivation through phosphorylation of TRP by PKC.  InaD acts a scaffold to organize a complex that mediates light activated signaling events.