Glycosylation of proteins from sugar nucleotides by whole cells. Effect of ammonium chloride treatment on mouse thymocytes

Abstract : When thymocytes are treated with iso-osmotic NH4Cl, the sugar incorporation into endogenous acceptors from labelled sugar nucleotides is largely increased compared with that in control thymocytes. This effect was obtained with labelled GDP-mannose, UDP-galactose and CMP-N-acetylneuraminic acid. The stimulation observed with NH4Cl-treated thymocytes does not involve the glycosylation of exogenous acceptors, and it was proved that the NH4Cl treatment (1) does not stimulate glycosyltransferase activities themselves, (2) does not lead to the release of soluble lycosyltransferases as the result of an extensive lysis of the thymocytes and (3) does not cause the emergence of glycosyltransferases at the cell surface. In fact, electron-microscopy observations showed that, although marked changes had occurred in the cytoplasm, the plasma membrane is sufficiently maintained to allow the cell to keep roughly its original shape and to retain the intracellular vesicles. We thus demonstrate that this stimulation is due to an enhancement of the entry of sugar nucleotides into the cell. As demonstrated by the inclusion of Trypan Blue within the cells, and the non-stimulation of glycosylation of exogenous large-molecular-mass acceptors, the effect of NH4Cl seems to be limited to the penetration of small-molecular-sized compounds through the plasma membrane. Thus NH4Cl treatment allows the labelled sugar nucleotides to penetrate the cell and to behave as the cellular pool to be utilized for glycosylation by intracellular vesicles.
Type de document :
Article dans une revue
Biochemical Journal, Portland Press, 1983, 216, p. 681-686
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Soumis le : mercredi 20 octobre 2010 - 16:25:34
Dernière modification le : mardi 3 juillet 2018 - 11:23:32

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  • HAL Id : hal-00527949, version 1

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Roméo Cecchelli, René Cacan, Bernard Hoflack, André Verbert. Glycosylation of proteins from sugar nucleotides by whole cells. Effect of ammonium chloride treatment on mouse thymocytes. Biochemical Journal, Portland Press, 1983, 216, p. 681-686. 〈hal-00527949〉

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