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).

HA receptors mediate the uptake of HA into cells. CD44 consists of four functional domains, the extracellular distal domain being the HA-binding region (Culty et al. 1990, Asher & Bignami 1992). The receptor for hyaluronan mediated motility (RHAMM, also called HMMR) can bind HA but not heparin or chondroitin sulfate (Assmann et al. 1998, Wang et al. 1996). Lymphatic vessel endothelial hyaluronic acid receptor 1 (LYVE1) removes HA from the lymphatic system (Banerji et al. 1999). It is present mainly on lymphatic endothelial cells but also in liver sinusoids. Hyaluronan receptor for endocytosis (HARE, stabilin-2, STAB2) binds to and mediates endocytosis of HA (Harris et al. 2007, Harris et al. 2004). HARE can also bind other glycosaminoglycans such as heparin (Harris et al. 2008).
High molecular weight HA is tethered to the cell surface by HA receptors and the GPI-linked hyaluronidase 2 (HYAL2) to form a HA:HAR:HYAL2 complex in the plasma membrane that localizes to caveolae (invaginations of the plasma membrane composed of cholesterol and gangliosides and rich in caveolin and flotillin).