Bora (D2B9) Rabbit mAb #12109

The eukaryotic cell cycle is carefully controlled by protein phosphorylation involving a number of phosphatases, kinases, and co-factors. Cyclin-dependent kinases (CDKs/cdcs), Polo-like kinases (PLKs), and Aurora kinases have been shown to be major regulators of mitotic control (reviewed in 1,2). Protein aurora borealis (Bora), a co-factor of Aurora-A first identified in Drosophila, also plays a key roll in cell cycle progression (3). Bora levels are low in G0/G1, increasing in S-phase and peaking at G2 (4).
Found to be conserved from C. elegans to humans, Bora is translocated from the nucleus to the cytoplasm upon activation of cdc2 at the onset of mitosis. Once present in the cytoplasm, Bora binds to and activates Aurora-A and PLK1 (3-5). It has been proposed that the binding of human Bora to PLK1 may lead to a conformational change in the protein that disrupts the autoinhibition by the Polo-Box Domain (PBD). This would allow for Thr210 on PLK1 to become more accessible for phosphorylation by Aurora-A (reviewed in 6). Active PLK1 then initiates the PLK1-cdc25-cdc2 positive feedback loop, leading to mitotic entry and the phosphorylation of Bora. Once phosphorylated in prophase, Bora is degraded allowing for normal mitotic progression (7).