Fig. 2. The cadherin-catenin complex in C. elegans. (A) Diagram of the cadherin-catenin complex in C. elegans. This complex consists of HMR-1A (cadherin), HMP-2 (ß-catenin), HMP-1 (-catenin) and JAC-1 (p120ctn). (B) A time course showing localization of the cadherin-catenin complex during epidermal morphogenesis in C. elegans. Confocal images of a living embryo expressing a JAC-1–GFP fusion protein. During ventral enclosure (a-b), edges of the epidermal cell sheet extend around the embryo, meet at the ventral midline, and seal through the formation of cell junctions. Note that JAC-1–GFP is not present at the leading edge of migrating epidermal cells, but is rapidly recruited to the contact region between cells at the ventral midline. Other adherens junctional components show a similar localization during enclosure. After ventral enclosure, contraction of the epidermis helps to drive the four-fold elongation of the embryo (c,d). Nomarski images of similarly aged embryos are shown for comparison (e-h). A Nomarski movie (Movie 4, http://jcs.biologists.org/supplemental/) showing development of a wild-type embryo is available online. In all images, anterior is left. Bar, 10 µm.