Immunocytochemical demonstration of the D2 protein in the presynaptic complex.

A monospecific antiserum against the rat brain synaptic plasma membrane protein D2 was produced by sequential immunization of rabbits with immunoprecipitates. This antiserum was used for immunoperoxidase localization of D2 in adult rat brain at both the light and the electron microscopal level. D2 was located in the presynaptic complex of neurons distributed ubiquitously in the brain. By gel electrophoresis D2 was demonstrated to exist in a perinatal form, which was desialylated during the ontogenetic period of maximal synaptogenesis.