RESUMO
Guanine aminohydrolase (GAH), one of purine metabolizing enzymes rich in the nervous system was proved to have identical amino acid sequence to a recently identified novel protein p51-nedasin, NE-dlg/SAP102-associated protein. Nedasin has been reported to localize at neuronal cell bodies and binds to SAP102, so it might have a role in modulating NMDA receptor 2B clustering of SAP102 or synaptic organization in neuronal cells. In this study, we localize GAH and SAP102 in rat retina using immunohistochemical method. Immunoreactivities are detected for both GAH and SAP102 in ganglion cell layer, inner plexiform layer, inner nuclear layer, outer plexiform layer and pigment layer. They seemed to be colocalized in ganglion cells, amacrine cells, horizontal cells and pigment cells. The staining profile for SAP102 is almost identical with NMDA receptor 2B mainly in fibrous elements in both the inner and outer plexiform layer. Our results support the possibility of close structural relationship between GAH and SAP102 in specific retinal cells and GAH involvement in synaptic organization association with SAP102 in the rat retina.