Luteinizing and follicle-stimulating hormones. Cell-free translations of messenger RNAs coding for subunit precursors.

Polyadenylated RNA prepared from pituitary glands of normal and castrate rats was translated in membrane-free heterologous cell-free systems derived from wheat germ and rabbit reticulocytes. Sodium dodecyl sufate (SDS)-polyacrylamide gel electrophoresis and autoradiography demonstrated a major [35S]methionine-labeled translation product of castrate pituitary mRNA with apparent Mr = 14,000. This Mr = 14,000 product was specifically immunoprecipitated by anti-sera to the alpha subunit of rat and bovine luteinizing hormone (LH alpha) and was much reduced in the translation products of normal pituitary RNA. Additional minor translation products of normal pituitary RNA. Additional minor translation products with apparent Mr = 15,000 and 16,000 were identified by immunoprecipitation with antisera to rat LH beta and to the beta subunit of rat follicle-stimulating hormone (FSH beta), respectively. The immunological identity of the alpha, LH beta, and FSH beta precursors was confirmed by successful competition of these immunoprecipitation reactions by unlabeled homologous LH alpha, LH beta, and FSH, respectively. These results indicate that the gonadotropin subunits are synthesized as precursors from separate mRNAs. This system is responsive to endocrine manipulations and is appropriate for studies of the regulation of gonadotropin biosynthesis.