Glutamine synthetase isoforms in leaves of a C4 plant: Sorghum vulgare

In Sorghum vulgare L. (cv. INRA 450) leaves, two isoforms of glutamine synthetase GS1 and GS2 were identified by DEAE Sephacel chromatography and polyac-rylamide gel electrophoresis. GS1 was present both in etiolated and green leaves and its activity remained constant during the greening process. In green leaves another isoform GS2 was identified that was responsible for a 33% increase in total glutamine synthetase activity after light exposure. The two isoforms differed in their heat stability but exhibited similar pH optima and Km values for L-glutamate. The total glutamine synthetase activity was equally distributed between mesophyll and bundle sheath cells; moreover in the two types of cells both GS1 and GS2 were present in the proportions of 67% and 33% of the total respectively. In mesophyll cells the two isoforms had a different subcellular distribution: GS2 was localized in the chloroplast and GS1 in the cytosol.

[1]  B. Hirel,et al.  Glutamine Synthetase Isoforms in Pea Leaves: Intracellular Localization , 1981 .

[2]  B. Hirel,et al.  Glutamine Synthetase in Rice: A COMPARATIVE STUDY OF THE ENZYMES FROM ROOTS AND LEAVES. , 1980, Plant physiology.

[3]  D. Barratt.  Method for the detection of glutamine synthetase activity on starch gels , 1980 .

[4]  G. Stewart,et al.  Tissue localization of barley (Hordeum vulgare) glutamine synthetase isoenzymes , 1980, FEBS letters.

[5]  R. Moore,et al.  Nitrogen Assimilation Pathways in Leaf Mesophyll and Bundle Sheath Cells of C(4) Photosynthesis Plants Formulated from Comparative Studies with Digitaria sanguinalis (L.) Scop. , 1979, Plant physiology.

[6]  B. Hirel,et al.  Occurrence and influence of light on the relative proportions of two glutamine sythetases in rice leaves , 1979 .

[7]  G. Stewart,et al.  Identification of two forms of glutamine synthetase in barley (Hordeum vulgare). , 1979, Biochemical and biophysical research communications.

[8]  S. Stasiewicz,et al.  Isolation and characterization of two forms of glutamine synthetase from soybean hypocotyl , 1979 .

[9]  B. Miflin,et al.  Distribution of the Enzymes of Nitrogen Assimilation within the Pea Leaf Cell. , 1979, Plant physiology.

[10]  T. Yoneyama,et al.  Amino acid metabolism in plant leaf IV. The effect of light on ammonium assimilation and glutamine metabolism in the cells isolated from spinach leaves , 1978 .

[11]  B. Miflin,et al.  Photorespiratory nitrogen cycle , 1978, Nature.

[12]  M. Hatch.  A simple spectrophotometric assay for fumarate hydratase in crude tissue extracts. , 1978, Analytical biochemistry.

[13]  W. Jackson,et al.  A mechanism for nitrate transport and reduction , 1977 .

[14]  J. Jacquot,et al.  Identification of a protein factor involved in dithiothreitol activation of NADP malate dehydrogenase from french bean leaves , 1976, FEBS letters.

[15]  B. Miflin,et al.  The pathway of nitrogen assimilation in plants , 1976 .

[16]  E. Hewitt.  Assimilatory Nitrate-Nitrite Reduction , 1975 .

[17]  V. Das,et al.  Nitrate metabolism in relation to the aspartate-type C-4 pathway of photosynthesis in Eleusine coracana , 1974 .

[18]  C. Neyra,et al.  Nitrite assimilation and amino nitrogen synthesis in isolated spinach chloroplasts. , 1974, Plant physiology.

[19]  K. Joy,et al.  Localisation of glutamine synthetase in chloroplasts. , 1973, Nature: New biology.

[20]  G. Edwards,et al.  Separation of mesophyll protoplasts and bundle sheath cells from maize leaves for photosynthetic studies. , 1973, Plant physiology.

[21]  N. Tolbert,et al.  Intracellular location of nitrate reductase and nitrite reductase. I. Spinach and tobacco leaves. , 1972, Biochimica et biophysica acta.

[22]  M. S. Naik,et al.  Role of light in the synthesis of nitrate reductase and nitrite reductase in rice seedlings. , 1972, The Biochemical journal.

[23]  E. B. Tregunna,et al.  The localization of nitrate-assimilating enzymes in leaves of plants with the C4-pathway of photosynthesis , 1971 .

[24]  M. D. Hatch,et al.  Distribution of enzymes in mesophyll and parenchyma-sheath chloroplasts of maize leaves in relation to the C4-dicarboxylic acid pathway of photosynthesis. , 1969, The Biochemical journal.

[25]  J. Bruinsma.  A comment on the spectrophotometric determination of chlorophyll. , 1961, Biochimica et biophysica acta.