title: Structural basis of the Axin-adenomatous polyposis coli interaction.
abstract: Axin and the adenomatous polyposis coli (APC) tumor suppressor protein are components of the Wnt/Wingless growth factor signaling pathway. In the absence of Wnt signal, Axin and APC regulate cytoplasmic levels of the proto-oncogene beta-catenin through the formation of a large complex containing these three proteins, glycogen synthase kinase 3beta (GSK3beta) and several other proteins. Both Axin and APC are known to be critical for beta-catenin regulation, and truncations in APC that eliminate the Axin-binding site result in human cancers. A protease-resistant domain of Axin that contains the APC-binding site is a member of the regulators of G-protein signaling (RGS) superfamily. The crystal structures of this domain alone and in complex with an Axin-binding sequence from APC reveal that the Axin-APC interaction occurs at a conserved groove on a face of the protein that is distinct from the G-protein interface of classical RGS proteins. The molecular interactions observed in the Axin-APC complex provide a rationale for the evolutionary conservation seen in both proteins.
authors.affiliation: Department of Structural Biology, Stanford University School of Medicine, 299 Campus Drive West, Stanford, CA 94305, USA.
authors.forename: K E
authors.initials: KE
authors.lastname: Spink
authors.forename: P
authors.initials: P
authors.lastname: Polakis
authors.forename: W I
authors.initials: WI
authors.lastname: Weis
mesh_terms: D025601:Adenomatous Polyposis Coli Protein; D000595:Amino Acid Sequence; D000818:Animals; D060466:Axin Protein; D001665:Binding Sites; D003598:Cytoskeletal Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008969:Molecular Sequence Data; D016296:Mutagenesis; D011485:Protein Binding; D011487:Protein Conformation; D011506:Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D000090063:Proto-Oncogene Mas; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D012097:Repressor Proteins; D016415:Sequence Alignment; D015398:Signal Transduction; D051153:Wnt Proteins; D014981:Xenopus; D029867:Xenopus Proteins; D029961:Zebrafish Proteins
chemical_list: D025601:Adenomatous Polyposis Coli Protein; D060466:Axin Protein; D003598:Cytoskeletal Proteins; C000715470:MAS1 protein, human; D011506:Proteins; D000090063:Proto-Oncogene Mas; D011518:Proto-Oncogene Proteins; D012097:Repressor Proteins; D051153:Wnt Proteins; D029867:Xenopus Proteins; D029961:Zebrafish Proteins; C555454:axin1 protein, Xenopus