Molecular Components of Vesicle Cycling at the Rod Photoreceptor Ribbon Synapse

Rod photoreceptors are light-sensitive neurons of the retina that support vision in dim light. A rod cell consists of an outer segment for phototransduction, an inner segment and soma for energy production and protein synthesis, and a synaptic terminal for vesicle release onto second-order neurons-bipolar and horizontal cells. Mouse rods contain a single ribbon synaptic release site, where vesicles filled with glutamate are released at a rate of up to ~20 vesicles/synapse/second. This high release rate requires a fine balance between synaptic vesicle exocytosis and endocytosis. Here, we review the properties of synaptic transmission and highlight proteins essential for synaptic vesicle recycling at the rod ribbon synapse.