Immunoelectrophoretic determination of brain-specific antigens in bulk-prepared neuronal and glial cells

The relative amounts of brain-specific antigens, S-100, glial fibrillary acidic protein (GFA), 14.3.2, synaptin C1, D1, D2 and D3 were determined by crossed immunoelectrophoresis in bulk-prepared neuronal, glial and synaptosomal fractions from 35-day-old rat brains. Little enrichment was ontained for any antigen in the neuronal perikaryal fraction. The glial fraction showed a 3.5-fold enrichment in GFA but had levels similar to whole brain with respect to S-100. Synaptosomes were somewhat enriched in the synaptin C1 protein, but did not differ markedly from whole brain with respect to the most antigens. The extent of cross-contamination in the various fractions could be judged only tentatively, partly due to differences in extractability of the proteins.