title: Pre-proparathyroid hormone: fidelity of the translation of parathyroid messenger RNA by extracts of wheat germ.
abstract: Pre-proparathyroid hormone is the major protein synthesized in wheat-germ extracts in response to addition of an 8-15S fraction of parathyroid RNA. The accuracy of the translation of the mRNA from parathyroid tissue was examined by analysis of the carboxyl-terminal tryptic peptide and the amino-terminal amino acid of the protein, by analysis of the size distribution of the mRNA, and by translation of the mRNA in a second cell-free extract. When 8-15S RNA was fractionated on a sucrose gradient containing formamide, RNA that supported the synthesis of pre-proparathyroid hormone was present in a single symmetrical peak, suggesting that it was homogeneous. Analyses by paper chromatography and electrophoresis of the proline-containing tryptic peptides of pre-proparathyroid hormone indicate that they are identical with the corresponding proline-containing peptides of parathyroid hormone. Because the COOH-terminal tryptic peptide of parathyroid hormone contains proline, the data indicate that the COOH termini of pre-proparathyroid hormone and parathyroid hormone are identical. Methionine from initiator [35S]Met-tRNAfMet was rapidly incorporated into pre-proparathyroid hormone by the wheat-germ extract, and a single-step Edman degradation selectively removed almost all of the initiator [35S]methionine present in pre-proparathyroid hormone. Translation of the 8-15S RNA in a cell-free extract from Krebs-II ascites cells resulted in a protein that comigrated with pre-proparathyroid hormone on sodium dodecyl sulfate-acrylamide gel electrophoresis. These data support the conclusion that the wheat-germ system accurately translates the mRNA for parathyroid hormone, and they strengthen the contention that pre-proparathyroid hormone is the initial biosynthetic product.
mesh_terms: D000818:Animals; D002417:Cattle; D008239:Lysine / Q000378:metabolism; D008715:Methionine / Q000378:metabolism; D010280:Parathyroid Glands / Q000378:metabolism*; D010281:Parathyroid Hormone / Q000096:biosynthesis*; D010442:Peptide Chain Initiation, Translational; D011392:Proline / Q000378:metabolism; D014176:Protein Biosynthesis; D011498:Protein Precursors / Q000096:biosynthesis*; D012333:RNA, Messenger / Q000378:metabolism*; D012639:Seeds / Q000378:metabolism*; D014908:Triticum / Q000378:metabolism
chemical_list: D010281:Parathyroid Hormone; D011498:Protein Precursors; D012333:RNA, Messenger; D011392:Proline; D008715:Methionine; D008239:Lysine