The protein levels of aurora kinase A (AURKA) during mitotic entry and in early mitosis can be reduced by the action of the SCF-FBXL7 E3 ubiquitin ligase complex consisting of SKP1, CUL1, RBX1 and FBXL7 subunits. FBXL7 is the substrate recognition subunit of the SCF-FBXL7 complex that associates with the centrosome-bound AURKA, promoting its ubiquitination and proteasome-mediated degradation. Overexpression of FBXL7 results in G2/M cell cycle arrest and apoptosis (Coon et al. 2011).
FBXL7 protein levels are down-regulated by the action of the SCF-FBXL18 E3 ubiquitin ligase complex, consisting of SKP1, CUL1, RBX1 and the substrate recognition subunit FBXL18. FBXL18 binds to the FQ motif of FBXL7, targeting it for ubiquitination and proteasome-mediated degradation, counteracting its pro-apoptotic activity (Liu et al. 2015). Cell cycle stage-dependency of down-regulation of FBXL7 by FBXL18 is unknown.