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The adenomatous polyposis coli tumor suppressor (APC) protein downregulates the oncogenic b-catenin in the Xenopus Wnt-1 signaling pathway. Mutations of APC that eliminate this function lead to sporadic and familial colon cancer. The APC protein is regulated in part by its binding to b-catenin and GSK3b, two proteins that bind directly to the APC phosphorylation sites. The b-catenin binding site within APC is located in the region that is deleted by cancer-associated APC mutations. We have shown that the human Axin protein binds directly to both b-catenin and GSK3b in vitro, and that endogenous hAxin coexists with these proteins in cells. URL https://www.bosterbio.com/anti-apc2-antibody-a06153-boster.html

Anti-APC2 Antibody Online: How to Choose the Right One

 

Yeast two-hybrid and immunoprecipitation assays demonstrate that Axin interacts with both the central domain of APC (amino acids 1034-2130) and the carboxy-terminal fragment, designated APC3, which contains the regulator of G-protein signaling domain (RGS). Deletion of amino acid 9-320 of hAxin, which contains the RGS domain, eliminated binding to APC2, but not to b-catenin or GSK3b. Moreover, immunoprecipitation of hAxin from SW480 and HCT116 colorectal cancer cell lines cotransfected with one plasmid encoding the indicated APC fragment fused to the GAL4 DNA-binding domain and the other encoding a Myc epitope tag, reveals that the endogenous b-catenin-Axin interaction is mediated by the Axin RGS domain.

In a GSK3b assay, hAxin dramatically enhanced the phosphorylation of APC25 when present in the reaction. This enhancement was not observed in the absence of GSK3b or when hAxin was replaced with a GST-hAxin construct that lacks the APC-binding domain. Moreover, overexpression of hAxin in SW480 cells dramatically decreased the levels of b-catenin in the cytoplasm.