Ultrastructural localization of gangliosides; GM1 is concentrated in caveolae

The ultrastructural distribution of the ganglioside GM1 was investigated in A431 cells. After fixation, the cells were frozen in liquid nitrogen, freeze-substituted, and then embedded in Lowicryl resin at -45 degrees C. By use of the cholera toxin-binding subunit adsorbed to gold as a specific probe...

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Bibliographic Details
Published in:The journal of histochemistry and cytochemistry 1994-02, Vol.42 (2), p.155-166
Main Author: Parton, RG
Format: Article
Language:English
Subjects:
Biological and medical sciences
Carrier Proteins - metabolism
Caveolin 1
Caveolins
Cell Membrane - metabolism
Cell Membrane - ultrastructure
Cholera Toxin
Diverse techniques
Endocytosis
Freeze Substitution
Fundamental and applied biological sciences. Psychology
G(M1) Ganglioside - metabolism
Gold Colloid
Golgi Apparatus - metabolism
Golgi Apparatus - ultrastructure
Humans
Ligands
Membrane Proteins - metabolism
Microscopy, Electron - methods
Molecular and cellular biology
Organelles - metabolism
Organelles - ultrastructure
Tissue Embedding
Tumor Cells, Cultured
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Summary:The ultrastructural distribution of the ganglioside GM1 was investigated in A431 cells. After fixation, the cells were frozen in liquid nitrogen, freeze-substituted, and then embedded in Lowicryl resin at -45 degrees C. By use of the cholera toxin-binding subunit adsorbed to gold as a specific probe to label on the sections, GM1 was shown to be present in endocytic organelles, in the trans-Golgi network, and on the plasma membrane, but was not detectable in the endoplasmic reticulum. GM1 was not distributed uniformly over the plasma membrane but was concentrated approximately four-fold in non-coated invaginations. These were identified as caveolae by labeling frozen sections of cholera toxin-gold surface-labeled cells with antibodies to VIP-21/caveolin. The results strengthen the functional analogy between caveolae and sorting domains of the TGN in polarized epithelial cells.
ISSN:0022-1554
1551-5044
DOI:10.1177/42.2.8288861