Structural highlights
Function[POP1_CAEEL] Part of the Wnt signaling pathway essential for the specification of the mesodermal cell fate in early embryos. Required for asymmetrical division of somatic gonadal precursor descendants which initiate axis formation required to control organ shape. Represses expression of target genes via its interaction with hda-1 histone deacetylase.[1] [2] Publication Abstract from PubMedC. elegans SYS-1 has key functional characteristics of a canonical beta-catenin, but no significant sequence similarity. Here, we report the SYS-1 crystal structure, both on its own and in a complex with POP-1, the C. elegans TCF homolog. The two structures possess signature features of canonical beta-catenin and the beta-catenin/TCF complex that could not be predicted by sequence. Most importantly, SYS-1 bears 12 armadillo repeats and the SYS-1/POP-1 interface is anchored by a conserved salt-bridge, the "charged button." We also modeled structures for three other C. elegans beta-catenins to predict the molecular basis of their distinct binding properties. Finally, we generated a phylogenetic tree, using the region of highest structural similarity between SYS-1 and beta-catenin, and found that SYS-1 clusters robustly within the beta-catenin clade. We conclude that the SYS-1 protein belongs to the beta-catenin family and suggest that additional divergent beta-catenins await discovery. The C. elegans SYS-1 protein is a bona fide beta-catenin.,Liu J, Phillips BT, Amaya MF, Kimble J, Xu W Dev Cell. 2008 May;14(5):751-61. PMID:18477457[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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