Association to HeLa cells and surface behavior of exogenous gangliosides studied with a fluorescent derivative of GM1
- Univ. of Milan (Italy)
Cultured HeLa cells were incubated with pyrene-GM1/{sup 3}H-radiolabeled GM1 ganglioside (1:4 M/M) mixtures for various times. The process of association of pyrene-GM1 with cells was qualitatively and quantitatively the same as that of {sup 3}H-GM1. The pyrene-GM1 and {sup 3}H-GM1 proportions in the various forms of association with cells were similar to that of the starting ganglioside mixture. After 2-h incubation, the association of ganglioside with cells was well established whereas almost no metabolic processing had occurred. During a 24-h incubation, pyrene- and {sup 3}H-GM1 underwent similar metabolic processing and gave rise to catabolic (GM2 and GM3) and anabolic (GDla) derivatives. Fluorescence spectroscopy experiments carried out with the excimer formation technique on subcellular fractions containing plasma membranes showed that exogenous ganglioside was, in part, associated with the cells in a micellar form removable by trypsin treatment, and in part inserted in a seemingly molecular dispersion. Addition of Ca{sup 2+} salts caused aggregation of the ganglioside, as indicated by the increase of the excimer:monomer fluorescence ratio. The phenomenon was Ca{sup 2+} concentration dependent (maximum at 10 mM), and subsequent addition of EDTA has no effect. The saccharide portion of exogenously incorporated pyrene-GM1 was available to interact with external ligands, as shown by its ability to bind cholera toxin whose addition reduced the collision rate among the ganglioside lipid moieties.
- OSTI ID:
- 7064416
- Journal Information:
- Biochemistry; (USA), Journal Name: Biochemistry; (USA) Vol. 29:3; ISSN 0006-2960; ISSN BICHA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
59 BASIC BIOLOGICAL SCIENCES
ALKALINE EARTH METAL COMPOUNDS
AROMATICS
CALCIUM COMPOUNDS
CARBOHYDRATES
CATIONS
CELL CONSTITUENTS
CELL CULTURES
CELL MEMBRANES
CHARGED PARTICLES
CHROMATOGRAPHY
CONDENSED AROMATICS
EMISSION SPECTROSCOPY
FLUORESCENCE SPECTROSCOPY
GANGLIOSIDES
GLYCOLIPIDS
HELA CELLS
HYDROCARBONS
HYDROGEN COMPOUNDS
IONS
LIGANDS
LIPIDS
MEMBRANES
ORGANIC COMPOUNDS
PYRENE
RADIOCHROMATOGRAPHY
SACCHARIDES
SEPARATION PROCESSES
SPECTROSCOPY
TRITIUM COMPOUNDS