The cellular localization of the two brain specific proteins, S-100 and 14-3-2

An attempt has been made to localize, at a cellular level, the two brain specific proteins, S-100 and 14-3-2, by determining their relative concentrations in thalamic nuclei undergoing retrograde cell degeneration after appropriate lesions of the cerebral cortex. As the neuronal degeneration progresses the concentration of the 14-3-2 protein declines so that 6 weeks postoperatively it is only approximately 40% of its control level. On the other hand, there is a slight, but statistically significant, increase in the level of the S-100 protein between the 1st and 4th postoperative weeks which appears to be correlated with the early gliosis in the affected nuclei. On this basis it is suggested that 14-3-2 is primarily a neuronal protein and that the S-100 protein is largely, if not exclusively, confined to glial cells.