C. Mirre et al., DETERGENT-RESISTANT MEMBRANE MICRODOMAINS FROM CACO-2 CELLS DO NOT CONTAIN CAVEOLIN, American journal of physiology. Cell physiology, 40(3), 1996, pp. 887-894
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 fr
om Caco-2 and A 431 cells showed the same morphological aspect by elec
tron microscopy and peaked at the same isopycnic density on sucrose gr
adients. Detergent-resistant microdomains from Caco-2 cells were enric
hed in glycosyl phosphatidylinositol (GPI)-anchored proteins, in sucra
se-isomaltase, an apical marker, and in most of the proteins found in
caveolin-rich membranes such as src-like proteins, fimbrin, ezrin, and
G(i) alpha. Caveolae-like structures were present in A 431 but absent
from Caco-2 cells at the electron microscopic level. Detergent-resist
ant microdomains from Caco-2 cells resemble caveolin-rich microdomains
in their molecular composition but do not seem to derive from morphol
ogically identified caveolae. Our results also indicate that caveolin
is not necessary for sorting of GPI-Linked proteins to the apical memb
rane of Caco-2 cells.