O. Baumann, Posterior midgut epithelial cells differ in their organization of the membrane skeleton from other Drosophila epithelia, EXP CELL RE, 270(2), 2001, pp. 176-187
In epithelial cells, the various components of the membrane skeleton are se
gregated within specialized subregions of the plasma membrane, thus contrib
uting to the development and stabilization of cell surface polarity. It has
previously been shown that, in various Drosophila epithelia, the membrane
skeleton components ankyrin and alpha beta -spectrin reside at the lateral
surface, whereas alpha beta (H)-spectrin is restricted to the apical domain
. By use of confocal immunofluorescence microscopy, the present study chara
cterizes the membrane skeleton of epithelial cells in the posterior midgut,
leading to a number of unexpected results. First, ankyrin and alpha beta -
spectrin are not detected on the entire lateral surface but appear to be re
sticted to the apicolateral area, codistributing with fasciclin III at smoo
th septate junctions. The presumptive ankyrin-binding proteins neuroglian a
nd Na+,K+-ATPase, however, do not colocalize with ankyrin. Second, alpha be
ta (H)-spectrin is enriched at the apical domain but is also present in low
er amounts on the entire lateral surface, colocalizing apicolaterally with
ankyrin/alpha beta -spectrin. Finally, despite the absence of zonulae adher
entes, F-actin, beta (H)-spectrin, and nonmuscle myosin-II are enriched in
the midlateral region. Thus, the model established for the organization of
the membrane skeleton in Drosophila epithelia does not hold for the posteri
or midgut, and there is quite some variability between the different epithe
lia with respect to the organization of the membrane skeleton. (C) 2001 Aca
demic Press.