Fig. 3. VAB-19::GFP localization to epidermal attachment structures. Because the endogenous VAB-19::GFP fluorescence signal is weak, we used anti-GFP antibodies to visualize VAB-19::GFP expression. (A) At comma stage, VAB-19::GFP was diffusely expressed in dorsal epidermal cells; the uneven expression might reflect differential onset of VAB-19 expression in different cells. (B) During early elongation (1.5-fold), the VAB-19::GFP signal began to accumulate in the regions within dorsal epidermal cells that contact body muscles (arrow). (C) During the intermediate stage of elongation (1.75-fold), VAB-19::GFP mostly localized to epidermal regions adjacent to body wall muscle. (D) During later elongation (threefold stage), VAB-19::GFP was organized in circumferential bands in muscle-adjacent epidermis. Inset (E), higher magnification of the VAB-19::GFP pattern at the threefold stage. (F) In adult epidermal cells, the full length VAB-19::GFP protein is localized to attachment structures. GFP fusions to VAB-19 N-terminal fragments containing residues 1-684 (not shown) or 1-294 (G) display subcellular localization identical to that of the full-length protein. (H) GFP fusions to the VAB-19 ankyrin repeat-containing domain (residues 1-43 and 697-1040) were not localized within epidermal cells. None of the truncated protein constructs rescued vab-19 mutant phenotypes; transgenes containing VAB-19(1-294)::GFP conferred a weak Vab phenotype in a wild-type background. Scale bars, 10 µm.