Targeting Protein For Xklp2 (TPX2)

TPX2 coimmunoprecipitated specifically with STK6 (AURKA) from mitotic HeLa cell extracts. Conversely, STK6 could be detected in TPX2 immunoprecipitates. Binding studies demonstrated that the N terminus of TPX2 directly interacted with the C-terminal catalytic domain of STK6. Although kinase activity was not required for their interaction, TPX2 was readily phosphorylated by STK6. Upon small interfering RNA (siRNA)-mediated elimination of TPX2 from cells, the association of STK6 with the spindle microtubules was abolished, although its association with spindle poles was unaffected. Conversely, depletion of STK6 by siRNA had no detectable influence on the localization of TPX2. The full-length C20ORF1 cDNA encodes a 747-amino acid protein with a putative ATP/GTP-binding site motif.