Western blot analysis and protein identification of the synaptosomal fraction. (A) To verify the enrichment of the synaptosomes, we performed Western blot analysis with known synaptic markers. We observed a dramatic increase in the immunoreactivity of synapsin-1 (I, presynaptic marker) and PSD-95 (II, postsynaptic marker) in the synaptosomal fraction (S) compared with unfractionated homogenate (H). In addition, we also observe an increase in the immunoreactivity of cytochrome c oxidase (IV, mitochondria marker) in the synaptosomal fraction consistent with the synaptic localization of mitochondria. We, however, observed more immunoreactivity of H3 histone (III) in the homogenate consistent with its localization in the nucleus and not in the synapses. In this study, we identified 4001 proteins (C) and 56,684 peptides (B).
