Pontin52, an interaction partner of beta-catenin, binds to the TATA box binding protein.
beta-catenin, the vertebrate homolog of the Drosophila Armadillo protein, has been shown to have dual cellular functions, as a component of both the cadherin-catenin cell adhesion complex and the Wnt signaling pathway. At Wnt signaling, beta-catenin becomes stabilized in the cytoplasm and subsequently available for interaction with transcription factors of the lymphocyte enhancer factor-1/T-cell factor family, resulting in a nuclear localization of beta-catenin. Although beta-catenin does not bind DNA directly, its carboxyl- and amino-terminal regions exhibit a transactivating activity still not well understood molecularly. Here we report the identification of an interaction partner of beta-catenin, a nuclear protein designated Pontin52. Pontin52 binds beta-catenin in the region of Armadillo repeats 2-5 and, more importantly, also binds the TATA box binding protein. We provide evidence for an in vivo multiprotein complex composed of Pontin52, beta-catenin, and lymphocyte enhancer factor-1/T-cell factor. Our results suggest involvement of Pontin52 in the nuclear function of beta-catenin.
Bauer
A
A
Department of Molecular Embryology, Max Planck Institute of Immunobiology, Stübeweg 51, D-79108 Freiburg, Germany.
Huber
O
O
Kemler
R
R
D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D003598:Cytoskeletal Proteins / Q000235:genetics* / Q000378:metabolism; D004247:DNA / Q000235:genetics / Q000378:metabolism; D004330:Drosophila; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000235:genetics* / Q000378:metabolism; D051381:Rats; D012441:Saccharomyces cerevisiae; D016415:Sequence Alignment; D016385:TATA Box / Q000235:genetics*; D015534:Trans-Activators; D015533:Transcriptional Activation; D051176:beta Catenin
C495268:Ctnnb1 protein, rat; D003598:Cytoskeletal Proteins; D009687:Nuclear Proteins; D015534:Trans-Activators; D051176:beta Catenin; D004247:DNA