In Vitro Synthesis of NADPH-Adrenodoxin Reductase and Adrenodoxin of Bovine Adrenal Cortex, and the Existence of a Large Precursor of Adrenodoxin1

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Abstract
Cytoplasmic free and bound polysomes isolated from bovine adrenal cortex were used to program protein synthesis in rat liver cell sap (175,000×g soluble material) and wheat germ lysate S-175 (175,000×g soluble material) systems. Both free and bound polysomes were translated with high fidelity and equal efficiency in the cell-free systems. Synthesis of adrenodoxin reductase (AdR) and adrenodoxin (Ad) in the cell-free systems was determined by the immunoprecipitation of the translation products using monospecific antibodies, and we found that AdR was synthesized by free polysomes whereas Ad was synthesized by both free and bound polysomes as a large precursor (pAd) having a molecular weight of approximately 22,000 daltons, which is about 10,000 daltons larger than mature Ad. The existence of a large precursor of Ad was also confirmed by its synthesis in a cell-free system programmed by total RNA isolated from bovine adrenal cortex. Bovine adrenal cortex mito chondria imported in vitro-synthesized AdR and pAd to the inside of the organelle in the absence of protein synthesis in a cell-free system, and processed pAd to the mature form during the import. These results suggest that cytoplasmically synthesized AdR and Ad are translocated posttranslationally into the matrix of mitochondria in adrenal cortex cells.

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