S-100 protein synthesis by isolated polyribosomes from rat brain.

The radioactive proteins synthesized in a cell-free system and released from polyribosomes from rat brain were analyzed for the presence of a protein found only in the nervous system. Polyribosomes from rat liver were also studied to demonstrate the organ specificity of the radioactive product synthesized in vitro. The S-100 protein constituted 0.15 percent of the radioactive proteins released from brain polyribosomes.