Detergent-resistant membrane microdomains from Caco-2 cells do not contain caveolin.
In this study we analyzed the relationship between detergent-resistant microdomains and caveolae in Caco-2 cells. Caveolin was not detected on Western blots or Northern blots or by immunoprecipitation in these cells, in contrast to A 431 cells. Triton X-100-resistant membranes from Caco-2 and A 431 cells showed the same morphological aspect by electron microscopy and peaked at the same isopycnic density on sucrose gradients. Detergent-resistant microdomains from Caco-2 cells were enriched in glycosyl phosphatidylinositol (GPI)-anchored proteins, in sucrase-isomaltase, an apical marker, and in most of the proteins found in caveolin-rich membranes such as src-like proteins, fimbrin, ezrin, and Gi alpha. Caveolae-like structures were present in A 431 but absent from Caco-2 cells at the electron microscopic level. Detergent-resistant microdomains from Caco-2 cells resemble caveolin-rich microdomains in their molecular composition but do not seem to derive from morphologically identified caveolae. Our results also indicate that caveolin is not necessary for sorting of GPI-linked proteins to the apical membrane of Caco-2 cells.
Mirre
C
C
Institut de Biologie du Développement de Marseille, Faculté des Sciences de Luminy, Marseille, France.
Monlauzeur
L
L
Garcia
M
M
Delgrossi
M H
MH
Le Bivic
A
A
D018938:Caco-2 Cells; D051242:Caveolin 1; D022461:Caveolins; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D003902:Detergents / Q000494:pharmacology*; D017261:Glycosylphosphatidylinositols / Q000378:metabolism; D006801:Humans; D008565:Membrane Proteins / Q000378:metabolism*; D008854:Microscopy, Electron; D017830:Octoxynol / Q000494:pharmacology*
C495540:CAV1 protein, human; D051242:Caveolin 1; D022461:Caveolins; D003902:Detergents; D017261:Glycosylphosphatidylinositols; D008565:Membrane Proteins; D017830:Octoxynol