A mode of regulation of beta-catenin signaling activity in Xenopus embryos independent of its levels Journal Article

Authors: Guger, K. A.; Gumbiner, B. M.
Article Title: A mode of regulation of beta-catenin signaling activity in Xenopus embryos independent of its levels
Abstract: The signaling activity of β-catenin is thought to be regulated by phosphorylation of a cluster of N-terminal serines, putative sites for GSK3β. In the prevailing model in the literature, GSK3β-dependent phosphorylation of these sites targets β-catenin for ubiquitin-mediated degradation. Wnt signaling inhibits GSK3β activity and this blocks degradation, allowing β-catenin to accumulate and signal. We show here that β-catenin activity is not regulated solely by protein stability. Mutations in the putative GSK3β phosphorylation sites of β-catenin enhance its signaling activity, but this cannot be accounted for by accumulation of either total or cadherin-free protein. Instead, the mutant protein has a threefold higher specific activity than the wild type both in vivo and in an in vitro signaling assay. We conclude that the N-terminal serines convey a layer of regulation upon β-catenin signaling in addition to the effects these sites exert upon protein stability. (C) 2000 Academic Press.
Keywords: signal transduction; protein phosphorylation; gene mutation; mutation; nonhuman; ubiquitin; animals; serine; embryo; protein stability; phosphorylation; vertebrata; embryo, nonmammalian; regulatory mechanism; amino acid sequence; molecular sequence data; amino terminal sequence; protein-serine-threonine kinases; gene control; trans-activators; beta catenin; cadherins; body patterning; aspartic acid; microinjections; gene activity; cytoskeletal proteins; xenopus; gsk3β; xenopus proteins; trixis; priority journal; article; wnts
Journal Title: Developmental Biology
Volume: 223
Issue: 2
ISSN: 0012-1606
Publisher: Elsevier Inc.  
Date Published: 2000-07-15
Start Page: 441
End Page: 448
Language: English
DOI: 10.1006/dbio.2000.9770
PUBMED: 10882528
PROVIDER: scopus
Notes: Export Date: 18 November 2015 -- Source: Scopus
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