Regulation and function of the interaction between the APC tumour suppressor protein and EB1.
The interaction between the adenomatous polyposis coli (APC) tumour suppressor and the microtubule-associated protein EB1 was examined. Immunoprecipitation suggested that APC and EB1 were not associated in cultures of HCT116 cells arrested in mitosis. The C-terminal 170 amino acids of APC, purified as a bacterial fusion protein, precipitated EB1 from cell extracts, significantly refining the location of the EB1 interaction domain in APC. In vitro phosphorylation of this fusion protein by either protein kinase A or p34cdc2 reduced its ability to bind to EB1. Expression of GFP fusions to C-terminal APC sequences lacking or including the APC basic domain but encompassing the EB1 binding region in SW480 cells revealed a microtubule tip association which co-localized with that of EB1. Expression of the basic domain alone revealed a non-specific microtubule localization. In vitro interaction studies confirmed that the APC basic domain did not contribute to EB1 binding. These findings strongly suggest that the interaction between APC and EB1 targets APC to microtubule tips, and that the interaction between the two proteins is down-regulated during mitosis by the previously described mitotic phosphorylation of APC.
Askham
J M
JM
Molecular Medicine Unit, University of Leeds, Clinical Sciences Building, St. James's University Hospital, Leeds LS9 7TF, UK.
Moncur
P
P
Markham
A F
AF
Morrison
E E
EE
D025601:Adenomatous Polyposis Coli Protein; D000595:Amino Acid Sequence; D003598:Cytoskeletal Proteins / Q000378:metabolism*; D006801:Humans; D008869:Microtubule-Associated Proteins / Q000378:metabolism*; D008870:Microtubules / Q000378:metabolism; D008938:Mitosis; D008969:Molecular Sequence Data; D009363:Neoplasm Proteins / Q000378:metabolism; D010766:Phosphorylation; D014407:Tumor Cells, Cultured
D025601:Adenomatous Polyposis Coli Protein; D003598:Cytoskeletal Proteins; C405804:EB1 microtubule binding proteins; D008869:Microtubule-Associated Proteins; D009363:Neoplasm Proteins