Cell‐free Protein Synthesis by Mouse Brain During Early Development

Abstract —Cell‐free homogenates were employed to study the nature of the mechanism that is responsible for the rapid decrement in protein synthesis during early neural development. There was a progressive loss of polypeptide synthesis in post‐mitochondrial fractions that were isolated from increasingly older tissue. By the time the animals were approximately 17 days old, the rate of amino acid incorporation had decreased to the rate that was measured in adult brain preparations. This decrement in synthetic activity was similar to that previously measured in developing intact brain cells. The loss in protein synthesis was demonstrated to be independent of cellular membrane permeability and under the influence of intracellular control mechanisms. Although the nature of the control mechanism is still not clear, a lack of template RNA to direct protein synthesis was not the limiting factor in the decreased synthesis of the older brain preparations.