Premium
Glutamine synthetase isoforms in leaves of a C 4 plant: Sorghum vulgare
Author(s) -
Hirel Bertrand,
Gadal Pierre
Publication year - 1982
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.1982.tb00579.x
Subject(s) - glutamine synthetase , gene isoform , etiolation , chloroplast , biochemistry , biology , hordeum vulgare , cytosol , isozyme , glutamine , enzyme , botany , microbiology and biotechnology , gene , poaceae , amino acid
In Sorghum vulgare L. (cv. INRA 450) leaves, two isoforms of glutamine synthetase GS 1 and GS 2 were identified by DEAE Sephacel chromatography and polyac‐rylamide gel electrophoresis. GS 1 was present both in etiolated and green leaves and its activity remained constant during the greening process. In green leaves another isoform GS 2 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 GS 1 and GS 2 were present in the proportions of 67% and 33% of the total respectively. In mesophyll cells the two isoforms had a different subcellular distribution: GS 2 was localized in the chloroplast and GS 1 in the cytosol.