Detergent resistant membrane microdomains from caco-2 cells do not
contain caveolin.
Mirre, Christian, Laure Monlauzeur, Martine Garcia, Marie
-H[acute]el[grave]ene Delgrossi, and Andr[acute]e Le Bivic.
IBDM, Facult[acute]e des Sciences de Luminy, 13288 Marseille Cedex
09, France and Facult[acute]e des Sciences de Poitiers, 40 Av. du
Recteur Pineau, 86000 Poitiers cedex 22
APStracts 3:0079C, 1996.
In this study we analyzed the relationship between detergent-
resistant microdomains and caveolae in Caco-2 cells. Caveolin was not
detected on Western blots, Northern blots or by immunoprecipitation
in these cells, in contrast to A431 cells. Triton X-100 resistant
membranes from Caco-2 and A431 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 (SI), an apical marker, and
in most of the proteins found in caveolin-rich membranes such as src
-like proteins, fimbrin, ezrin and G[alpha]i. Caveolae -like
structures were present in A431 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.
Received 18 October 1995; accepted in final form 1 March 1996.
APS Manuscript Number C633-5.
Article publication pending Am. J. Physiol. (Cell Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 20 March 96