Immunocytochemical localization of the D2-protein in rat retina.

The localization of the D2-protein in rat retina was investigated by quantitative immunoelectrophoresis and by immunoperoxidase staining on both the light microscopic and the electron microscopic level. The D2-protein was enriched 1.4 times in retina compared to whole brain and its was located to most presynaptic and some postsynaptic membranes in the inner an outer plexiform layers. Moreover, the D2-protein was located on the cell membrane confining the ciliary neck region connecting the inner and the outer segments of photoreceptor cells. Thus, on the electron microscopic level, the D2-protein is not restricted to the presynaptic membrane, but it is also found in other parts of the neuronal surface membrane.