Fig. 4. Conserved regions required for Nullo function. Hunter C et al. Mol. Biol. Cell 2002;13:146-157 Copyright © 2002 The American Society for Cell Biology Conserved regions required for Nullo function. (A) Western blot showing the expression of the C-terminal deletions ΔA–ΔE. Expression of the endogenous Nullo protein is shown in the first lane. The extracts from ΔA–ΔD contain both the endogenous protein (upper band) and the deletion protein (lower band), which is present at levels equal to or greater than that of the endogenous protein. The last two lanes show extracts from wild-type and ΔE embryos in which Nullo was detected using an alternate mAb, 2F8-18. These lanes indicate that the ΔE protein is expressed at lower levels than the endogenous protein. (B) Embryos expressing only a specific deletion form of Nullo were stained with anti-Nullo antibodies to determine the subcellular localization of the mutant proteins. The top panel of each set shows a surface view, and the bottom panel shows a cross section of the cellularization front. ΔA and ΔB have a subcellular distribution similar to wild-type, but fail to rescue thenullo mutant phenotype. ΔC and ΔD also show a normal localization pattern and in addition are able to rescue the defects in basal junction formation. Only weak ΔE staining was detected using the 2F8-18 antibody, but there appears to be some staining above background at the level of the basal junction. Nullo-X embryos lacking a transgene are shown as a negative control. Scale bar, 10 μm.