The zinc fingers of BuGZ directly bind to the kinase domain of AurA. (A and B) Immunoprecipitation (IP) using BuGZ (A) or AurA (B) antibodies in mitotic HeLa cell lysates. Equivalent of 1% of the input lysate and 20% of total immunoprecipitates were loaded. (C and D) Immunoprecipitation using xBuGZ (rabbit polyclonal IgG; r IgG; C) or xAurA (mouse polyclonal IgG; m IgG; D) antibodies in XEEs. Equivalent of 0.2% of the input lysate and 30% of total immunoprecipitates were loaded. (E) Schematic of xBuGZ with NLS, zinc fingers (ZnFs), and the C-terminal region as well as YFP-tagged xBuGZ used in the study. (F) Purified YFP, YFP-xBuGZ, YFP-xBuGZΔ7, YFP-xBuGZΔN58, or YFP-xBuGZΔN92 were incubated with purified xAurA, followed by pulldown with antibody to YFP and then Western blotting and Coomassie Brilliant blue (CBB) staining. (G) Purified GST or GST-xBuGZ(8–58) was incubated with purified xAurA in the presence or absence of EDTA followed by GST pulldown, Western blotting, and Coomassie blue staining. (H) Purified GST, GST-xAurA, GST-xAurA(1–25), GST-xAurA(26–126), or GST-xAurA(127–407) were incubated with YFP or YFP-xBuGZ followed by GST pulldown, Western blotting, and Coomassie blue staining. For G and H, 0.1% of total reaction and 10% of total xBuGZ pulldowns were analyzed by Western blotting. 1% of total reaction and 10% of total pulldowns were analyzed by Coomassie blue staining.