Figure 1.

Glutamate cascade proteins expressed in dendritic tips of ON BCs. Glutamate released from photoreceptor terminals in the dark binds the mGluR6 metabotropic glutamate receptor and activates the alpha subunit of a heterotrimeric G-protein, Gα_o. Dissociation of G-protein subunits culminates in closure of the non-selective cation channel, TRPM1. Gα_o is inactivated by the β subunit (β5) and by a GTPase activating the regulator of G-protein signaling complex. A leucine-rich repeat protein, NYX, is required for the correct localization of TRPM1, whereas GPR179, another G-protein receptor, mediates channel sensitivity. LRIT3 interacts with both NYX and TRPM1.