Innexins undergo a developmental shift in apico-basal distribution in salivary gland cells but other markers of apical location (eg. Na+ /K+ ATPase α subunit) do not.
A GFP-tagged allele of the endogenous Na+ /K+ ATPase α subunit (ATPα-GFP) reveals higher levels of this protein at the apical (lumen) end of pupal salivary gland cells, just as it is in embryos. A, ATPα-GFP staining intensity at the basal (non-lumen) end of cells is significantly less than at the apical (lumen) end of cells. Arrows show different ends (apical/basal) of the same cells in each image. B, Rotation of a three-dimensional reconstruction of the salivary gland permits a side view of the cells (final frame). This confirms that there is a higher level (greater fluorescence) of ATPα-GFP at the apical end of these cells. The ATPα-GFP reporter line used here was AtpαG00109.