In vitro synthesis of a thyroglobulin precursor by porcine thyroid membrane-bound ribosomes in a heterologous cell-free system.

The synthesis of a thyroglobulin precursor directed by endogenous messenger RNA has been achieved in a heterologous cell-free system containing porcine thyroid membrane-bound ribosomes and rat brain cortex cell sap. The main features of the system, such as ion and nucleotide requirements, temperature, dependence, inhibitors sensitivity, and ability to reinitiate, were studied. The nature of the product has been determined by specific immunoprecipitation and its size has been estimated by sucrose density gradient and sodium dodecyl sulfate acrylamide gel electrophoresis. Under our conditions, the thyroglobulin precursor was mainly synthesized by membrane-bound ribosomes.