TPX2 binds to aurora kinase A (AURKA) at centrosomes. The first 43 amino acids at the N-terminus of TPX2 are needed for binding to AURKA (Bayliss et al. 2003). HMMR (RHAMM) binds to TPX2 (Groen et al. 2004, Maxwell et al. 2005) and is involved in the proper localization of TPX2 to centrosomes and TPX2-mediated AURKA activation (Chen et al. 2014, Scrofani et al. 2015).
TPX2 binding to Aurora A protects premature AURKA degradation by APC/C-mediated proteolysis during early mitosis. TPX2 differentially regulates AURKA stability, activity and localization. While amino acids 1-43 in TPX2 facilitate complex formation between AURKA and TPX2 and promote kinase activation, they are insufficient for AURKA targeting to the mitotic spindle (Giubettini et al. 2011).