Cytosolic glutamine synthetase in higher plants

Hirel, Bertrand; McNally, Sheila F.; Gadal, Pierre; Sumar, N.; Stewart, George R.

doi:10.1111/j.1432-1033.1984.tb07881.x

Cited by 48 publications

(24 citation statements)

References 21 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Although cytosolic GS isoenzymes from other plants have a similar amino acid composition but with a slightly different molecular mass (single subunit of 41000 Da) they do not contain any carbohydrate components (not shown). The presence of carbohydrates detected in the chloroplastic GS (5%) might explain the slight difference observed in the subunit molecular mass and the specific immunological behaviour of the various cytosolic and chloroplastic isoforms from higher plants [ 11, 121. It has been previously demonstrated, using specific antibodies prepared against either chloroplastic or cytosolic GS, that each isoenzyme possesses very different antigenic determinants, and it was therefore concluded that they were probably different proteins.…”

Section: Resultsmentioning

confidence: 99%

Chloroplastic glutamine synthetase from tobacco leaves: a glycosylated protein

et al. 1984

Self Cite

View full text Add to dashboard Cite

The amino acid and carbohydrate content of chloroplastic glutamine synthetase from tobacco leaves has been analysed. The enzyme subunit contanins 5% carbohydrate, mainly represented by glucosamine, galactosamine, glucose, galactose and mannose residues. The enzyme subunit displayed a single band of molecular mass 44000 Da after sodium dodecyl sulphate (SDS) electrophoresis. However, when isoelectrofocussing electrophoresis was performed, four subunits were evident differing by their charge. Furthermore, the four different subunits stained positively when tested with periodic acid Shiff reagent, showing that sugars and amino sugars were present within all the subunits.

show abstract

Section: Resultsmentioning

confidence: 99%

Chloroplastic glutamine synthetase from tobacco leaves: a glycosylated protein

et al. 1984

Self Cite

View full text Add to dashboard Cite

show abstract

“…Only one form has been described in the roots of different plants (4,7,14), this root form comigrates with the GS, leaf form when both are analyzed by ion exchange chromatography (7,10,14). However, the root form in barley and rice are different from the two forms of GS in leaves (7,8). Recently it has been established that the multiple forms ofGS in Phaseolus vulgaris are the result oftheir different polypeptide composition (1 1).…”

mentioning

confidence: 99%

Expression of Two Different Glutamine Synthetase Polypeptides during Root Development in Phaseolus vulgaris L.

Ortega¹,

Campos²,

Sánchez³

et al. 1986

Plant Physiol.

View full text Add to dashboard Cite

Immunoprecipitation and two-dimensional gel electrophoresis analysis ofthe glutamine synthetase (GS) polypeptides (a and ,) during Phaswolus vulgaris root development shows that the a polypeptide is the main component of the enzyme in the embryo and in up to 5 day old roots.From 5 days on, the 6 polypeptide becomes the root predominant GS monomer. The a/,@ ratio of the in vitro translated GS polypeptides from the total polysomal RNA isolated at different root ages correlates with the a/f ratio observed in the root extracts. These results suggest that the two root GS polypeptides are encoded by different mRNA species in Phaseolus vulgaris.Glutamine synthetase (GS2) (EC 6.3.1.2) is a key enzyme for

show abstract

“…Glutamine synthetase exists in two isoforms (GS,2 and GS2) in the leaf cells of some higher plants (13,15), which have previously been compared and studied by immunological methods (1,9).…”

mentioning

confidence: 99%

Immunocytolocalization of Glutamine Synthetase in Green Leaves and Cotyledons of Lycopersicon esculentum

Botella¹,

Verbelen²,

Valpuesta³

1988

Plant Physiol.

View full text Add to dashboard Cite

ABSTRACrGlutamine synthetase was localized in leaves and cotyledons of young tomato (Lycopersicon esculentum Mill.) plants using immunogold techniques coupled to transmission electron microscopy. The enzyme occurs only in chloroplasts and is most probably a stroma constituent.Glutamine synthetase exists in two isoforms (GS,2 and GS2) in the leaf cells of some higher plants (13,15), which have previously been compared and studied by immunological methods (1, 9).The intracellular localization of GS isoforms was initially investigated by classical subcellular fractionation in aqueous and nonaqueous media. GS, was specifically associated with the cytosolic fraction, whereas GS2 was present in the chloroplast fraction (7,8,14,18).Specific antibodies prepared against GS2 from spinach leaves (10) were used to study the intracellular localization of GS in sections of spinach leaves by indirect immunofluorescence. These experiments confirmed that spinach GS2 is specifically localized in the chloroplast.Recently, a detailed cellular and subcellular localization of GS in cyanobacteria was carried out (3, 12) by immunogold techniques (6) coupled to transmission electron microscopy. The enzyme was present in all cell types with no specific label associated with subcellular inclusions. Green leaves of tomato plants contain only one GS isoenzyme (15), which has been purified to homogeneity (5). The kinetics and heat stability of this enzyme suggest it to be chloroplastic in nature (4, 5, 15). However, this enzyme has not been localized at the subcellular level.In this report, we present for the first time the application of immunogold techniques to study the localization of GS2 in the leaves and cotyledons of a higher plant (Lycopersicon esculentum). Electron Microscopic Techniques. Plastic Embedding. Leaves and cotyledons were cut in small pieces and fixed in 3% paraformaldehyde, 0.5% glutaraldehyde in 0.1 M sodium phosphate buffer (pH 7.3) for 3 h followed by dehydration in ethanol (50-80-100%). Samples were embedded in L.R. White resin (London Resin Co. Ltd., UK) which was then polymerized at 60°C.Ultrathin sections (0.05 Am) were cut with a Sorvall ultramicrotome MT2-B and placed on Formvar-coated copper grids.Immunogold staining. The samples were washed twice for 10 min with 0.1 M sodium phosphate buffer (pH 7.3) containing glycine (0.75 mg/mL) and 0.1% BSA. They were then incubated for 45 min with immunoaffinity purified antibodies against GS2(30 tg/mL) diluted with phosphate buffer; washed three times in phosphate buffer containing 0.1% BSA; and incubated for 30 min in goat anti-rabbit IgG conjugated with 15 nm gold particles (GAR 15, Janssen Pharmaceutica, Beerse, Belgium), diluted 1:30 (v/v) in phosphate buffer containing 0.1% BSA. The samples were washed three times in phosphate buffer containing 0.1 % BSA, followed by three washings with phosphate buffer and double-distilled water.The control sections were prepared by the same procedure used for the experimental sections but nonimmune serum was used instead of an...

show abstract

Cytosolic glutamine synthetase in higher plants

Cited by 48 publications

References 21 publications

Chloroplastic glutamine synthetase from tobacco leaves: a glycosylated protein

Chloroplastic glutamine synthetase from tobacco leaves: a glycosylated protein

Expression of Two Different Glutamine Synthetase Polypeptides during Root Development in Phaseolus vulgaris L.

Immunocytolocalization of Glutamine Synthetase in Green Leaves and Cotyledons of Lycopersicon esculentum

Contact Info

Product

Resources

About