P-Rex2 is localized to ribbon synaptic terminals of bipolar cells in the IPL. Confocal imaging of P-Rex2 and VGluT1 labeling in the IPL (Single optical plane of approximately 0.3 μm thickness shown). A: P-Rex2 labeling is present in discrete puncta (arrowheads) located throughout the depth of the IPL. B: Labeling for VGluT1 identifies bipolar cell terminals throughout the IPL. The large terminals of rod bipolar cells along the inner edge of the IPL are prominently labeled. C: Labeling for P-Rex2 colocalizes extensively with VGluT1 labeling, indicating that P-Rex2 is localized to many bipolar cell terminals. Nuclei are counterstained with DAPI (blue) in panel A to illustrate the location of the INL and GCL. INL, inner nuclear layer; IPL, inner plexiform layer; GCL, ganglion cell layer. Scale bars = 20 μm.