In addition to its presence at the vicinity of NPCs, we have shown previously that RanBP2 is localized to and abundant in the mitochondria-rich ellipsoid subcellular compartment of photosensory (photoreceptor) neurons of the retina [19]. We extended the subcellular colocalization studies on RanBP2 and its novel partners by immunocytochemistry to determine if RanBP2, Cox11, HKI, and mHsp70 colocalize in hippocampal neurons (Figure 3A–3C), cerebral cortex neurons (Figure 3D–3F), ellipsoid (mitochondria-rich) subcellular compartments of photosensory neurons of the retina (Figure 3G–3O), and dissociated primary glia and neuron cultures from the brain (Figure 3P–3Z). Double immunostaining with antibodies against these proteins showed that they colocalize to the mitochondria (Figure 3A–3Z).