Fig. 2. Molecular basis of pop-1(Sys) mutations. (A) Diagram of POP-1 protein. A ß-catenin binding domain resides at the N terminus (blue) and an HMG DNA binding domain is located centrally (red). Sites of pop-1(Sys) lesions are marked. (B) pop-1(q645) is predicted to change a conserved aspartic acid (D) to glutamic acid (E) in the ß-catenin binding domain. (C) pop-1(q624) is predicted to change a conserved asparagine (N) to isoleucine (I) in the HMG box. Each alignment includes human LEF-1 (hlef-1), murine TCF-4 (mtcf-4), Xenopus TCF-3 (xtcf-3), Drosophila Pangolin (pan), and C. elegans POP-1.