1v18
From Proteopedia
THE CRYSTAL STRUCTURE OF BETA-CATENIN ARMADILLO REPEAT COMPLEXED WITH A PHOSPHORYLATED APC 20MER REPEAT.
Overview
The transcriptional coactivator beta-catenin mediates Wnt growth factor signaling. In the absence of a Wnt signal, casein kinase 1 (CK1) and glycogen synthase kinase-3beta (GSK-3beta) phosphorylate cytosolic beta-catenin, thereby flagging it for recognition and destruction by the ubiquitin/proteosome machinery. Phosphorylation occurs in a multiprotein complex that includes the kinases, beta-catenin, axin, and the Adenomatous Polyposis Coli (APC) protein. The role of APC in this process is poorly understood. CK1epsilon and GSK-3beta phosphorylate APC, which increases its affinity for beta-catenin. Crystal structures of phosphorylated and nonphosphorylated APC bound to beta-catenin reveal a phosphorylation-dependent binding motif generated by mutual priming of CK1 and GSK-3beta substrate sequences. Axin is shown to act as a scaffold for substrate phosphorylation by these kinases. Phosphorylated APC and axin bind to the same surface of, and compete directly for, beta-catenin. The structural and biochemical data suggest a novel model for how APC functions in beta-catenin degradation.
About this Structure
1V18 is a Protein complex structure of sequences from Homo sapiens and Mus musculus. Full crystallographic information is available from OCA.
Reference
Mechanism of phosphorylation-dependent binding of APC to beta-catenin and its role in beta-catenin degradation., Ha NC, Tonozuka T, Stamos JL, Choi HJ, Weis WI, Mol Cell. 2004 Aug 27;15(4):511-21. PMID:15327768 Page seeded by OCA on Sat May 3 11:57:42 2008
