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RIBOSOMAL RNA, FRACTION I PROTEIN SYNTHESIS, AND RIBULOSE DIPHOSPHATE CARBOXYLASE ACTIVITY IN DEVELOPING AND SENESCING LEAVES OF CUCUMBER
Author(s) -
CALLOW J. A.
Publication year - 1974
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/j.1469-8137.1974.tb04601.x
Subject(s) - ribosome , chloroplast , protein biosynthesis , ribosomal rna , biochemistry , enzyme , rna , fraction (chemistry) , rubisco , ribosomal protein , biology , chemistry , chromatography , gene
S ummary The synthesis of chloroplast ribosomes and Fraction I protein appear to be discrete events in the life of a leaf. Expanding cucumber leaves incorporated exogenous precursors of RNA and protein synthesis into chloroplastic rRNA and Fraction I respectively but, after full expansion, the synthesis of both of these components was greatly reduced while incorporation into cytoplasmic rRNA and other soluble proteins was still proceeding. It is suggested that the overall synthesis of whole molecules of Fraction I is controlled by the rate of synthesis, in the chloroplast of the large sub‐unit of Fraction I and that this in part is related to the availability of 70S ribosomes. RuDPcarboxylase activity paralleled Fraction I protein content in developing leaves, but as the leaves senesced, the enzymatic activity declined at a faster rate than the loss of Fraction I protein.