Storage protein precursor polypeptides in cotyledons of Pisum sativum L. Identification of, and isolation of a cDNA clone for, an 80000-Mr legumin-related polypeptide.
An 80 000-Mr polypeptide, which bound to anti-legumin IgG, was detected among labelled polypeptides from cotyledons at late stages of development. When poly(A)-containing RNA from similar cotyledons was translated in a cell-free protein-synthesizing system, an 80 000-Mr polypeptide was also detected. Immunoprecipitation of translation products with anti-legumin IgG showed that, in addition to the major legumin precursor polypeptides of Mr approximately 60 000, the 80 000-Mr polypeptide was specifically immunoprecipitated. A cDNA clone, pCD32, was found to select an RNA coding for an 80 000-Mr polypeptide in hybrid-selection experiments. Additional minor polypeptides of Mr 63 000 and 65 000 were present in translation products of RNA selected by pCD32; all three polypeptides were immunoprecipitated by anti-legumin IgG. Thermal elution of RNAs bound to pCD32 showed that the affinity of pCD32 to the RNA coding for the 80 000-Mr polypeptide was greater than to the RNAs coding for the 63 000-Mr and 65 000-Mr polypeptides. In similar hybrid-selection experiments, another cDNA clone, pCD40, selected RNAs coding predominantly for polypeptides of Mr 63 000 and 65 000. A minor polypeptide of Mr 80 000 was also detected among these products; again all three polypeptides were immunoprecipitated by anti-legumin IgG. Peptide mapping revealed close similarities between the 80000-Mr polypeptide and the 63 000-Mr/65 000-Mr polypeptides obtained by translation of RNAs selected by pCD32. There were similarities also between maps obtained from translation products of RNA selected by pCD32 and those obtained from anti-legumin IgG immunoprecipitates of total translation products of poly(A)-containing RNA.
D055598:Chemical Phenomena; D002621:Chemistry; D004247:DNA / Q000302:isolation & purification*; D007887:Fabaceae / Q000235:genetics / Q000378:metabolism*; D008715:Methionine / Q000302:isolation & purification; D008970:Molecular Weight; D009693:Nucleic Acid Hybridization; D010940:Plant Proteins; D014674:Plant Proteins, Dietary / Q000096:biosynthesis / Q000235:genetics*; D010946:Plants, Medicinal; D014176:Protein Biosynthesis; D011498:Protein Precursors / Q000235:genetics / Q000378:metabolism*; D013050:Spectrometry, Fluorescence; D000097793:Legumins
D004247:DNA; D008715:Methionine; D010940:Plant Proteins; D014674:Plant Proteins, Dietary; D011498:Protein Precursors; D000097793:Legumins